U.S. patent application number 13/057890 was filed with the patent office on 2011-06-09 for method for forming a multilayer coating film.
Invention is credited to Takato Adachi, Kazuaki Kitazono, Shuichi Nakahara.
Application Number | 20110135935 13/057890 |
Document ID | / |
Family ID | 41284192 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110135935 |
Kind Code |
A1 |
Adachi; Takato ; et
al. |
June 9, 2011 |
METHOD FOR FORMING A MULTILAYER COATING FILM
Abstract
An object of the present invention is to provide a method of
producing a multilayer coating film having excellent smoothness and
high distinctness of image. The method of forming a multilayer
coating film according to the present invention includes the steps
of: successively applying an aqueous intermediate coating
composition, an aqueous base coating composition, and a clear
coating composition to a substrate; and simultaneously heat-curing
the resulting intermediate, base, and clear coating layers, the
aqueous intermediate coating composition (X) comprising: a base
resin (A); a curing agent (B); and a diester compound (C), the
curing agent (B) being a polyisocyanate compound (B1) and/or a
polycarbodiimide compound (B2); and the diester compound (C) being
represented by formula (1): (wherein R.sup.1 and R.sup.2 are each
independently a hydrocarbon group having 4 to 18 carbon atoms,
R.sup.3 is an alkylene group having 2 to 4 carbon atoms, m is an
integer of 3 to 25, and m oxyalkylene units (R.sup.3--O) may be the
same or different). ##STR00001##
Inventors: |
Adachi; Takato; (Kanagawa,
JP) ; Kitazono; Kazuaki; (Kanagawa, JP) ;
Nakahara; Shuichi; (Aichi, JP) |
Family ID: |
41284192 |
Appl. No.: |
13/057890 |
Filed: |
August 10, 2009 |
PCT Filed: |
August 10, 2009 |
PCT NO: |
PCT/JP2009/064370 |
371 Date: |
February 7, 2011 |
Current U.S.
Class: |
428/422.8 ;
427/301; 428/473.5; 524/314 |
Current CPC
Class: |
B05D 7/14 20130101; C08K
3/013 20180101; C09D 5/36 20130101; C09D 7/61 20180101; B05D 7/572
20130101; Y10T 428/31721 20150401; Y10T 428/31547 20150401; B05D
2451/00 20130101; B05D 2451/00 20130101; B05D 2401/20 20130101;
B05D 2401/20 20130101; B05D 2401/40 20130101; B05D 2451/00
20130101; B05D 2401/20 20130101; B05D 2401/20 20130101 |
Class at
Publication: |
428/422.8 ;
427/301; 428/473.5; 524/314 |
International
Class: |
B32B 27/26 20060101
B32B027/26; B05D 3/10 20060101 B05D003/10; C08K 5/11 20060101
C08K005/11 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 2008 |
JP |
2008-208258 |
Aug 12, 2008 |
JP |
2008-208261 |
Claims
1. A method of forming a multilayer coating film comprising the
steps of: (1) applying an aqueous intermediate coating composition
(X) to a substrate to form an intermediate coating layer thereon;
(2) applying an aqueous base coating composition (Y) to the uncured
intermediate coating layer formed in step (1) to form a base
coating layer thereon; (3) applying a clear coating composition (Z)
to the uncured base coating layer formed in step (2) to form a
clear coating layer thereon; and (4) simultaneously heat-curing the
uncured intermediate coating, uncured base coating, and uncured
clear coating layers formed in steps (1) to (3), the aqueous
intermediate coating composition (X) comprising: a base resin (A);
a curing agent (B); and a diester compound (C), the curing agent
(B) being a polyisocyanate compound (B1) and/or a polycarbodiimide
compound (B2); and the diester compound (C) being represented by
formula (1): ##STR00006## (wherein R.sup.1 and R.sup.2 are each
independently a hydrocarbon group having 4 to 18 carbon atoms,
R.sup.3 is an alkylene group having 2 to 4 carbon atoms, m is an
integer of 3 to 25, and m oxyalkylene units (R.sup.3--O) may be the
same or different).
2. The method of forming a multilayer coating film according to
claim 1 wherein the base resin (A) is a hydroxy-containing resin
(A1), and the curing agent (B) is a polyisocyanate compound
(B1).
3. The method of forming a multilayer coating film according to
claim 2 wherein the hydroxy-containing resin (A1) is a
hydroxy-containing polyester resin (A1-1) and/or a
hydroxy-containing acrylic resin (A1-2).
4. The method of forming a multilayer coating film according to
claim 3 wherein the hydroxy-containing polyester resin (A1-1) is a
polyester resin containing a C.sub.4 or higher linear alkylene
group in an amount of 0.3 to 2.5 mol/kg (on a resin solids
basis).
5. The method of forming a multilayer coating film according to
claim 3 wherein the hydroxy-containing polyester resin (A1-1)
contains a benzene ring and/or a cyclohexane ring in such an amount
that the total amount of benzene ring and cyclohexane ring is in
the range of 1.5 to 4.0 mol/kg (on a resin solids basis).
6. The method of forming a multilayer coating film according to
claim 2 wherein the polyisocyanate compound (B1) is a
water-dispersible polyisocyanate compound.
7. The method of forming a multilayer coating film according to
claim 2 wherein the proportions of the hydroxy-containing resin
(A1), polyisocyanate compound (B1), and diester compound (C) are
such that the amount of hydroxyl-containing resin (A1) is 30 to 95
parts by mass, the amount of polyisocyanate compound (B1) is 5 to
70 parts by mass, and the amount of diester compound (C) is 1 to 30
parts by mass, per 100 parts by mass of the total amount of
hydroxy-containing resin (A1) and polyisocyanate compound (B1), on
a solids basis.
8. The method of forming a multilayer coating film according to
claim 1 wherein the base resin (A) is a carboxy-containing resin
(A2), and the curing agent (B) is a polycarbodiimide compound
(B2).
9. The method of forming a multilayer coating film according to
claim 8 wherein the carboxy-containing resin (A2) is a
carboxy-containing polyester resin (A2-1) and/or a
carboxy-containing acrylic resin (A2-2).
10. The method of forming a multilayer coating film according to
claim 9 wherein the carboxy-containing polyester resin (A2-1) is a
polyester resin containing a C.sub.4 or higher linear alkylene
group in an amount of 0.3 to 2.5 mol/kg (on a resin solids
basis).
11. The method of forming a multilayer coating film according to
claim 9 wherein the carboxy-containing polyester resin (A2-1)
contains a benzene ring and/or a cyclohexane ring in such an amount
that the total amount of benzene ring and cyclohexane ring is in
the range of 1.5 to 4.0 mol/kg (on a resin solids basis).
12. The method of forming a multilayer coating film according to
claim 8 wherein the proportions of the carboxy-containing resin
(A2), the polycarbodiimide compound (B2), and the diester compound
(C) are such that the amount of carboxy-containing resin (A2) is 30
to 95 parts by mass, the amount of polycarbodiimide compound (B2)
is 5 to 70 parts by mass, and the amount of diester compound (C) is
1 to 30 parts by mass, per 100 parts by mass of the total amount of
carboxy-containing resin (A2) and polycarbodiimide compound (B2),
on a solids basis.
13. The method of forming a multilayer coating film according to
claim 1 wherein the coating composition (X) contains a carboxy- and
hydroxy-containing resin (A3) as the base resin (A), a
polycarbodiimide compound (B2) as the curing agent (B), and further
contains an amino resin (B3).
14. The method of forming a multilayer coating film according to
claim 13 wherein the amino resin (B3) is a melamine resin (B3-1),
the melamine resin (B3-1) being a methyl-butyl mixed etherified
melamine resin having a methoxy/butoxy molar ratio in the range of
90/10 to 50/50.
15. The method of forming a multilayer coating film according to
claim 1 wherein the aqueous intermediate coating composition (X)
further contains a coloring pigment (D1) and/or an extender pigment
(D2) in such an amount that the total amount of coloring pigment
(D1) and extender pigment (D2) is in the range of 40 to 180 parts
by mass per 100 parts by mass of the total amount of base resin (A)
and curing agent (B), on a solids basis.
16. The method of forming a multilayer coating film according to
claim 1 wherein the aqueous base coating composition (Y) comprises
a luster pigment (D3).
17. The method of forming a multilayer coating film according to
claim 1 wherein the substrate is a vehicle body having an
undercoating layer formed thereon using an electrodeposition
coating composition.
18. An article having a multilayer coating film formed thereon by
the method of claim 1.
19. An aqueous intermediate coating composition for forming a
multilayer coating film comprising a base resin (A), a curing agent
(B), and a diester compound (C), the curing agent (B) being a
polyisocyanate compound (B1) and/or a polycarbodiimide compound
(B2); and the diester compound (C) being represented by formula
(1): ##STR00007## (wherein R.sup.1 and R.sup.2 are each
independently a hydrocarbon group having 4 to 18 carbon atoms,
R.sup.3 is an alkylene group having 2 to 4 carbon atoms, m is an
integer of 3 to 25, and m oxyalkylene units (R.sup.3--O) may be the
same or different).
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of forming a
multilayer coating film having excellent appearance, by a
3-coat-1-bake process comprising successively applying an aqueous
intermediate coating composition, an aqueous base coating
composition, and a clear coating composition to a substrate, and
heat-curing the resulting three layers simultaneously to form a
multilayer coating film.
BACKGROUND ART
[0002] A method of forming a multilayer coating film by a
3-coat-2-bake (3C2B) process is widely used as a method for forming
a coating film on automobile bodies. This method comprises the
following steps after applying an electrodeposition coating
composition to a substrate: application of an intermediate coating
composition.fwdarw.curing by baking.fwdarw.application of a base
coating composition.fwdarw.preheating (preliminary
heating).fwdarw.application of a clear coating
composition.fwdarw.curing by baking. However, in recent years, for
the purpose of saving energy, attempts have been made to omit the
bake-curing step that is performed after applying the intermediate
coating composition and use a 3-coat-1-bake (3C1B) process
comprising the following steps after applying an electrodeposition
coating composition to a substrate: application of an intermediate
coating composition.fwdarw.preheating (preliminary
heating).fwdarw.application of a base coating
composition.fwdarw.preheating (preliminary
heating).fwdarw.application of a clear coating
composition.fwdarw.curing by baking.
[0003] From the viewpoint of controlling the environmental
pollution caused by the vaporization of organic solvents, the
establishment of a 3-coat 1-bake process using an aqueous
intermediate coating composition and an aqueous base coating
composition is particularly desired.
[0004] However, the 3-coat 1-bake process using an aqueous
intermediate composition and an aqueous base coating composition
has the following drawback due to the use of water as a main
solvent in the composition. When an aqueous base coating
composition is applied to an intermediate coating layer, the
intermediate coating layer is dissolved by the water contained in
the aqueous base coating composition, thus forming a mixed layer at
the interface between the intermediate and base coating layers and
resulting in a coating film having low smoothness and low
distinctness of image. Particularly, when an aqueous base coating
composition containing a luster pigment is used, the mixed layer
distorts the orientation of the luster pigment contained in the
aqueous base composition, thus resulting in low flip-flop effect
and/or metallic mottling of the resulting coating film.
[0005] To solve the above problem, Patent Document 1 discloses a
method of forming a multilayer coating film comprising applying an
aqueous intermediate coating composition to a substrate to form an
intermediate coating layer thereon, applying an aqueous metallic
base coating composition to the intermediate coating layer to form
a metallic base coating layer thereon, and applying a clear coating
composition to the base coating layer to form a clear coating layer
thereon. Patent Document 1 describes that when the aqueous
intermediate coating composition and/or the aqueous metallic base
coating composition contains a polycarbodiimide compound and a
carboxy-containing aqueous resin, the resulting multilayer coating
film has excellent water resistance and high distinctness of image.
However, the coating film obtained by the method disclosed in
Patent Document 1 has insufficient smoothness.
[0006] Patent Document 2 discloses a method of forming a multilayer
coating film by a 3C1B process using an aqueous intermediate
coating composition (A), an aqueous base coating composition (B),
and a clear coating composition (C). According to Patent Document
2, the aqueous intermediate coating composition (A) contains a
polyester resin (X) and a curing agent (Y), and the polyester resin
(X) contains a benzene ring and a cyclohexane ring in an amount of
1.0 to 2.2 mol/kg (resin solids content) in total; and that the
curing agent (Y) is at least one compound selected from the group
consisting of isocyanate group-containing compounds (a), oxazoline
group-containing compounds (b), carbodiimide group-containing
compounds (c), hydrazide group-containing compounds (d), and
semicarbazide group-containing compounds (e). Patent Document 2
describes that the method disclosed therein can produce a
multilayer coating film having excellent smoothness, distinctness
of image, chipping resistance, and water resistance. However, even
when the method disclosed in Patent Document 2 is used, the
resulting multilayer coating film may be insufficient in terms of
smoothness and distinctness of image.
CITATION LIST
Patent Literature
[0007] PTL 1: Japanese Unexamined Patent Publication No. 2001-9357
[0008] PTL 2: WO 2007/126107
SUMMARY OF INVENTION
Technical Problem
[0009] An object of the present invention is to provide a method of
forming a multilayer coating film having excellent smoothness and
high distinctness of image, by a 3-coat 1-bake process comprising
successively applying an aqueous intermediate coating composition,
an aqueous base coating composition, and a clear coating
composition to a substrate, and simultaneously heat-curing the
resulting three layers to form a multilayer coating film, and in
particular to provide a method of forming a multilayer coating film
having an excellent appearance with a high flip-flop effect and
little metallic mottling when using an aqueous base coating
composition containing a luster pigment.
Solution to Problem
[0010] To achieve the above object, the present inventors carried
out extensive research. As a result, the inventors found that the
above object can be achieved by a 3-coat 1-bake process comprising
successively applying an aqueous intermediate coating composition,
an aqueous base coating composition, and a clear coating
composition to a substrate, and simultaneously heat-curing the
resulting three layers to form a multilayer coating film, while
using, as the intermediate coating composition, a specific coating
composition comprising a base resin (A), a specific curing agent
(B), and a diester compound (C) having a specific structure. The
present invention has been accomplished based on this finding.
[0011] The present invention provides a method of forming a
multilayer coating film, an aqueous intermediate coating
composition used in the method, and an article having a multilayer
coating film formed thereon by the method, as itemized below.
1. A method of forming a multilayer coating film comprising the
steps of: [0012] (1) applying an aqueous intermediate coating
composition (X) to a substrate to form an intermediate coating
layer thereon; [0013] (2) applying an aqueous base coating
composition (Y) to the uncured intermediate coating layer formed in
step (1) to form a base coating layer thereon; [0014] (3) applying
a clear coating composition (Z) to the uncured base coating layer
formed in step (2) to form a clear coating layer thereon; and
[0015] (4) simultaneously heat-curing the uncured intermediate
coating, uncured base coating, and uncured clear coating layers
formed in steps (1) to (3), [0016] the aqueous intermediate coating
composition (X) comprising: a base resin (A); a curing agent (B);
and a diester compound (C), [0017] the curing agent (B) being a
polyisocyanate compound (B1) and/or a polycarbodiimide compound
(B2); and [0018] the diester compound (C) being represented by
formula (1):
##STR00002##
[0018] (wherein R.sup.1 and R.sup.2 are each independently a
hydrocarbon group having 4 to 18 carbon atoms, R.sup.3 is an
alkylene group having 2 to 4 carbon atoms, m is an integer of 3 to
25, and m oxyalkylene units (R.sup.3--O) may be the same or
different). 2. The method of forming a multilayer coating film
according to item 1 wherein the base resin (A) is a
hydroxy-containing resin (A1), and the curing agent (B) is a
polyisocyanate compound (B1). 3. The method of forming a multilayer
coating film according to item 2 wherein the hydroxy-containing
resin (A1) is a hydroxy-containing polyester resin (A1-1) and/or a
hydroxy-containing acrylic resin (A1-2). 4. The method of forming a
multilayer coating film according to item 3 wherein the
hydroxy-containing polyester resin (A1-1) is a polyester resin
containing a C.sub.4 or higher linear alkylene group in an amount
of 0.3 to 2.5 mol/kg (on a resin solids basis). 5. The method of
forming a multilayer coating film according to item 3 wherein the
hydroxy-containing polyester resin (A1-1) contains a benzene ring
and/or a cyclohexane ring in such an amount that the total amount
of benzene ring and cyclohexane ring is in the range of 1.5 to 4.0
mol/kg (on a resin solids basis). 6. The method of forming a
multilayer coating film according to item 2 wherein the
polyisocyanate compound (B1) is a water-dispersible polyisocyanate
compound. 7. The method of forming a multilayer coating film
according to item 2 wherein the proportions of the
hydroxy-containing resin (A1), polyisocyanate compound (B1), and
diester compound (C) are such that the amount of
hydroxyl-containing resin (A1) is 30 to 95 parts by mass, the
amount of polyisocyanate compound (B1) is 5 to 70 parts by mass,
and the amount of diester compound (C) is 1 to 30 parts by mass,
per 100 parts by mass of the total amount of hydroxy-containing
resin (A1) and polyisocyanate compound (B1), on a solids basis. 8.
The method of forming a multilayer coating film according to item 1
wherein the base resin (A) is a carboxy-containing resin (A2), and
the curing agent (B) is a polycarbodiimide compound (B2). 9. The
method of forming a multilayer coating film according to item 8
wherein the carboxy-containing resin (A2) is a carboxy-containing
polyester resin (A2-1) and/or a carboxy-containing acrylic resin
(A2-2). 10. The method of forming a multilayer coating film
according to item 9 wherein the carboxy-containing polyester resin
(A2-1) is a polyester resin containing a C.sub.4 or higher linear
alkylene group in an amount of 0.3 to 2.5 mol/kg (on a resin solids
basis). 11. The method of forming a multilayer coating film
according to item 9 wherein the carboxy-containing polyester resin
(A2-1) contains a benzene ring and/or a cyclohexane ring in such an
amount that the total amount of benzene ring and cyclohexane ring
is in the range of 1.5 to 4.0 mol/kg (on a resin solids basis). 12.
The method of forming a multilayer coating film according to item 8
wherein the proportions of the carboxy-containing resin (A2), the
polycarbodiimide compound (B2), and the diester compound (C) are
such that the amount of carboxy-containing resins (A2) is 30 to 95
parts by mass, the amount of polycarbodiimide compound (B2) is 5 to
70 parts by mass, and the amount of diester compound (C) is 1 to 30
parts by mass, per 100 parts by mass of the total amount of
carboxy-containing resin (A2) and polycarbodiimide compound (B2),
on a solids basis. 13. The method of forming a multilayer coating
film according to item 1 wherein the coating composition (X)
contains a carboxy- and hydroxy-containing resin (A3) as the base
resin (A), a polycarbodiimide compound (B2) as the curing agent
(B), and further contains an amino resin (B3). 14. The method of
forming a multilayer coating film according to item 13 wherein the
amino resin (B3) is a melamine resin (B3-1), the melamine resin
(B3-1) being a methyl-butyl mixed etherified melamine resin having
a methoxy/butoxy molar ratio in the range of 90/10 to 50/50. 15.
The method of forming a multilayer coating film according to item 1
wherein the aqueous intermediate coating composition (X) further
contains a coloring pigment (D1) and/or an extender pigment (D2) in
such an amount that the total amount of coloring pigment (D1) and
extender pigment (D2) is in the range of 40 to 180 parts by mass
per 100 parts by mass of the total amount of base resin (A) and
curing agent (B), on a solids basis. 16. The method of forming a
multilayer coating film according to item 1 wherein the aqueous
base coating composition (Y) comprises a luster pigment (D3). 17.
The method of forming a multilayer coating film according to item 1
wherein the substrate is a vehicle body having an undercoating
layer formed thereon using an electrodeposition coating
composition. 18. An article having a multilayer coating film formed
thereon by the method of item 1. 19. An aqueous intermediate
coating composition for forming a multilayer coating film
comprising a base resin (A), a curing agent (B), and a diester
compound (C), the curing agent (B) being a polyisocyanate compound
(B1) and/or a polycarbodiimide compound (B2); and the diester
compound (C) being represented by formula (1):
##STR00003##
(wherein R.sup.1 and R.sup.2 are each independently a hydrocarbon
group having 4 to 18 carbon atoms, R.sup.3 is an alkylene group
having 2 to 4 carbon atoms, m is an integer of 3 to 25, and m
oxyalkylene units (R.sup.3--O) may be the same or different).
Advantageous Effects of Invention
[0019] According to the method of forming a coating film of the
present invention, a multilayer coating film having excellent
smoothness and excellent distinctness of image can be produced by a
3-coat 1-bake process comprising successively applying an aqueous
intermediate coating composition, an aqueous base coating
composition, and a clear coating composition to a substrate, and
simultaneously heat-curing the resulting three layers to form a
multilayer coating film. When using an aqueous base coating
composition containing a luster pigment, a multilayer coating film
having excellent appearance with a high flip-flop effect and little
metallic mottling can be formed.
DESCRIPTION OF EMBODIMENTS
[0020] The method of forming a multilayer coating film of the
present invention will be described below in more detail.
1. Step (1)
[0021] In step (1) of the method of forming a multilayer coating
film of the present invention, an aqueous intermediate coating
composition (X) is applied to a substrate. The aqueous intermediate
coating composition (X) comprises: a base resin (A); a curing agent
(B); and a diester compound (C),
the curing agent (B) being a polyisocyanate compound (B1) and/or a
polycarbodiimide compound (B2), and the diester compound (C) being
represented by formula (1):
##STR00004##
(wherein R.sup.1 and R.sup.2 are each independently a hydrocarbon
group having 4 to 18 carbon atoms, R.sup.3 is an alkylene group
having 2 to 4 carbon atoms, m is an integer of 3 to 25, and m
oxyalkylene units (R.sup.3--O) may be the same or different).
1.1 Substrate
[0022] The substrate to be coated with the aqueous intermediate
coating composition (X) is not particularly limited. Examples of
substrates include exterior panel parts of automobile bodies such
as passenger cars, trucks, motorcycles, and buses; automotive
components such as bumpers; exterior panel parts of household
electric appliances such as cellular phones and audio equipment;
etc. Among these substrates, exterior panel parts of automobile
bodies and automotive components are preferable.
[0023] The material for the substrate is not particularly limited.
Examples of the material include metallic materials such as iron,
aluminium, brass, copper, tin, stainless steel, galvanized steel,
steel plated with zinc alloys (Zn--Al, Zn--Ni, Zn--Fe, etc.);
plastic materials such as polyethylene resins, polypropylene
resins, acrylonitrile-butadiene-styrene (ABS) resins, polyamide
resins, acrylic resins, vinylidene chloride resins, polycarbonate
resins, polyurethane resins, epoxy resins, and like resins,
mixtures of these resins, and various types of fiber-reinforced
plastics (FRP); inorganic materials such as glass, cement, and
concrete; wood; textile materials such as paper and cloth; etc.
Among these materials, metallic materials and plastic materials are
particularly preferable.
[0024] The substrate may be a surface-treated substrate which may
further have a coating layer formed thereon. More specifically, the
substrate may be a metal material or a metal body formed of the
material as mentioned above, such as a vehicle body, which may be
subjected to a surface treatment, such as phosphate treatment,
chromate treatment, or composite oxide treatment, and which may be
further coated thereon.
[0025] Examples of the substrate having a coating layer formed
thereon include base materials whose surface is optionally treated
and which have an undercoating layer formed thereon. Among these,
vehicle bodies having an undercoating layer formed thereon using an
electrodeposition coating composition are preferable, and those
having an undercoating layer formed thereon using a cationic
deposition coating composition are particularly preferable.
[0026] The substrate may be a plastic material as mentioned above
or a plastic member formed therefrom, such as an automotive
component (or parts), which may have been surface-treated or coated
with a primer, etc. The substrate may be a combination of plastic
and metallic materials mentioned above.
1.2 Base Resin (A)
[0027] The resin that can be used as the base resin (A) is not
particularly limited. Examples of the base resin (A) include a
hydroxy-containing resin (A1), a carboxy-containing resin (A2), and
a carboxy- and hydroxy-containing resin (A3). Each of the resins is
described below.
1.2.1 Hydroxy-Containing Resin (A1)
[0028] The hydroxy-containing resin (A1) is a resin having at least
one hydroxy group per molecule. From the viewpoint of the water
resistance and other properties of the resulting coating film, the
hydroxy-containing resin (A1) preferably has a hydroxy value of
about 5 to about 300 mg KOH/g, more preferably about 15 to about
200 mg KOH/g, and even more preferably about 30 to about 180 mg
KOH/g.
[0029] The hydroxy-containing resin (A1) may have acid group(s) in
the molecule. Examples of the acid group include a carboxy group, a
sulfonic acid group, a phosphoric acid group, etc. It is
particularly preferable that the hydroxy-containing resin (A) have
one or more carboxy groups as the acid group. When the
hydroxy-containing resin (A1) has carboxy group(s), the
hydroxy-containing resin (A1) is a carboxy- and hydroxy-containing
resin (A3) as described below. The hydroxy-containing resin (A1)
can be made water soluble or water dispersible by neutralizing the
acid group(s) with a basic compound.
[0030] Examples of the basic compound include hydroxides of alkali
metals or alkaline earth metals such as sodium hydroxide, potassium
hydroxide, lithium hydroxide, calcium hydroxide, and barium
hydroxide; ammonia; primary monoamines such as ethylamine,
propylamine, butylamine, benzylamine, monoethanolamine,
neopentanolamine, 2-aminopropanol, 2-amino-2-methyl-1-propanol, and
3-aminopropanol; secondary monoamines such as diethylamine,
diethanolamine, di-n-propanolamine, di-iso-propanolamine,
N-methylethanolamine, and N-ethylethanolamine; tertiary monoamines
such as dimethylethanolamine, trimethylamine, triethylamine,
triisopropylamine, methyldiethanolamine, and
2-(dimethylamino)ethanol; polyamines such as diethylenetriamine,
hydroxyethylaminoethylamine, ethylaminoethylamine, and
methylaminopropylamine; etc.
[0031] From the viewpoint of the water resistance of the resulting
coating film, the amount of basic compound is preferably about 0.1
to about 1.5 equivalents, and more preferably about 0.2 to about
1.2 equivalents, relative to the acid groups of the
hydroxy-containing resin (A1).
[0032] When the hydroxy-containing resin (A1) contains acid
group(s), the hydroxy-containing resin (A1) preferably has an acid
value of about 3 to about 100 mg KOH/g, more preferably about 5 to
about 80 mg KOH/g, and even more preferably about 10 to about 70 mg
KOH/g, from the viewpoint of the storage stability of the immediate
coating composition (X), the water resistance of the resulting
coating film, etc. When a hydroxy-containing resin (A1) with an
acid value of 10 mg KOH/g or less is used, the hydroxy-containing
resin (A1) may be mixed with an emulsifier and agitated by applying
a mechanical shear force to forcibly disperse the
hydroxy-containing resin (A1) in water, instead of being
neutralized with a basic compound.
[0033] Examples of the hydroxy-containing resin (A1) include
polyester resins, acrylic resins, polyether resins, polycarbonate
resins, polyurethane resins, epoxy resins, alkyd resins, etc. Such
resins can be used singly or in a combination of two or more. It is
particularly preferable to use a hydroxy-containing polyester resin
(A1-1) and/or a hydroxy-containing acrylic resin (A1-2) as the
hydroxy-containing resin (A1), and it is more preferable that the
hydroxy-containing resin (A1) be a hydroxy-containing polyester
resin (A1-1).
[0034] It is also possible to use, as the hydroxy-containing resin
(A1), a so-called urethane-modified polyester resin or
urethane-modified acrylic resin, which is obtained by a urethane
reaction of a polyisocyanate compound with some of the hydroxy
groups of the hydroxy-containing polyester resin (A1-1) or
hydroxy-containing acrylic resin (A1-2) to extend the chain of the
resin to increase the molecular weight.
1) Hydroxy-Containing Polyester Resin (A1-1)
[0035] The hydroxy-containing polyester resin (A1-1) can be
produced by an esterification or transesterification reaction of an
acid component (a1-1) with an alcohol component (a1-2).
[0036] A compound that is typically used as an acid component to
produce a polyester resin can be used as the acid component (a1-1).
Examples of the acid component (a1-1) include an aliphatic
polybasic acid (a1-1-1), an alicyclic polybasic acid (a1-1-2), an
aromatic polybasic acid (a1-1-3), and the like.
[0037] The aliphatic polybasic acid (a1-1-1) is generally an
aliphatic compound having two or more carboxy groups per molecule;
an acid anhydride of the aliphatic compound; or an ester of the
aliphatic compound. Examples of the aliphatic polybasic acid
(a1-1-1) include aliphatic polycarboxylic acids such as butanedioic
acid (succinic acid), pentanedioic acid (glutaric acid),
hexanedioic acid (adipic acid), heptanedioic acid (pimelic acid),
octanedioic acid (suberic acid), nonanedioic acid (azelaic acid),
decanedioic acid (sebacic acid), undecanedioic acid, dodecanedioic
acid, tridecanedioic acid (brasylic acid), hexadecanedioic acid,
and octadecanedioic acid; anhydrides of these aliphatic
polycarboxylic acids; lower alkyl esters of these aliphatic
polycarboxylic acids; and the like. Such examples of the aliphatic
polybasic acid (a1-1-1) can be used singly or in a combination of
two or more.
[0038] From the viewpoint of the smoothness, distinctness of image,
water resistance, and chipping resistance of the resulting coating
film, it is preferable to use, as the aliphatic polybasic acid
(a1-1-1), an aliphatic dicarboxylic acid containing a C.sub.4 or
higher, preferably C.sub.4-18, and more preferably C.sub.6-12
linear alkyelene group. Examples of the aliphatic dicarboxylic acid
containing a C.sub.4 or higher linear alkylene group include
hexanedioic acid (adipic acid), heptanedioic acid (pimelic acid),
octanedioic acid (suberic acid), nonanedioic acid (azelaic acid),
decanedioic acid (sebacic acid), undecanedioic acid, dodecanedioic
acid, tridecanedioic acid (brasylic acid), hexadecanedioic acid,
and octadecanedioic acid; anhydrides of these aliphatic
dicarboxylic acids; lower alkyl esters of these aliphatic
dicarboxylic acids; and the like. Such compounds can be used singly
or in a combination of two or more.
[0039] The alicyclic polybasic acid (a1-1-2) is generally a
compound having one or more alicyclic structures (mainly 4- to
6-membered rings) and two or more carboxy groups per molecule; an
acid anhydride of the compound; or an ester of the compound.
Examples of the alicyclic polybasic acid (a1-1-2) include alicyclic
polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid,
1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,
4-cyclohexene-1,2-dicarboxylic acid,
3-methyl-1,2-cyclohexanedicarboxylic acid,
4-methyl-1,2-cyclohexanedicarboxylic acid,
1,2,4-cyclohexanetricarboxylic acid, and
1,3,5-cyclohexanetricarboxylic acid; anhydrides of these alicyclic
polycarboxylic acids; lower alkyl esters of these alicyclic
polycarboxylic acids; etc. Such examples of the alicyclic polybasic
acid (a1-1-2) can be used singly or in a combination of two or
more.
[0040] The aromatic polybasic acid (a1-1-3) is generally an
aromatic compound having two or more carboxy groups per molecule;
an acid anhydride of the aromatic compound; and an ester of the
aromatic compound. Examples of the aromatic polybasic acid (a1-1-3)
include aromatic polycarboxylic acids such as phthalic acid,
isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid,
4,4'-biphenyldicarboxylic acid, trimellitic acid, and pyromellitic
acid; anhydrides of these aromatic polycarboxylic acids; lower
alkyl esters of these aromatic polycarboxylic acids; and the like.
Such examples of the aromatic polybasic acid (a1-1-3) can be used
singly or in a combination of two or more.
[0041] It is particularly preferable to use, as the aromatic
polybasic acid (a1-1-3), phthalic acid, phthalic anhydride,
isophthalic acid, trimellitic acid, or trimellitic anhydride.
[0042] Examples of the acid component (a1-1) other than the
aliphatic polybasic acid (a1-1-1), alicyclic polybasic acid
(a1-1-2), and aromatic polybasic acid (a1-1-3) include fatty acids
such as palm oil fatty acid, cottonseed oil fatty acid, hempseed
oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall
oil fatty acid, soybean oil fatty acid, linseed oil fatty acid,
tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty
acid, dehydrated castor oil fatty acid, and safflower oil fatty
acid; monocarboxylic acids such as lauric acid, myristic acid,
palmitic acid, stearic acid, oleic acid, linolic acid, linolenic
acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexanoic acid,
and 10-phenyloctadecanoic acid; hydroxycarboxylic acids such as
lactic acid, 3-hydroxybutanoic acid, and 3-hydroxy-4-ethoxybenzoic
acid; and the like. Such examples of the acid component (a1-1) can
be used singly or in a combination of two or more.
[0043] A polyhydric alcohol having at least two hydroxy groups per
molecule can be preferably used as the alcohol component (a1-2).
Examples of the polyhydric alcohol include an aliphatic diol
(a1-2-1), an alicyclic diol (a1-2-2), an aromatic diol (a1-2-3),
and the like.
[0044] The aliphatic diol (a1-2-1) is generally an aliphatic
compound having two hydroxy groups per molecule. Examples of the
aliphatic diol (a1-2-1) include ethylene glycol, propylene glycol,
diethylene glycol, trimethylene glycol, tetraethylene glycol,
triethylene glycol, dipropylene glycol, 1,4-butanediol,
1,3-butanediol, 2,3-butanediol, 1,2-butanediol,
3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol,
1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol,
2,3-dimethyltrimethylene glycol, tetramethylene glycol,
3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol,
2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol,
1,4-hexanediol, 2,5-hexanediol, 1,9-nonanediol, 1,10-decanediol,
1,12-dodecanediol, neopentylglycol, and the like. Such compounds
can be used singly or in a combination of two or more.
[0045] From the viewpoint of the smoothness, distinctness of image,
chipping resistance, etc., of the resulting coating film, it is
preferable to use, as the aliphatic diol (a1-2-1), an aliphatic
diol containing a C.sub.4 or higher, preferably C.sub.4-12, and
more preferably C.sub.6-10 linear alkylene group. Examples of the
aliphatic diol containing C.sub.4 or higher linear alkylene group
include 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,
1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, etc. Such
compounds can be used singly or in a combination of two or
more.
[0046] The alicyclic diol (a1-2-2) is generally a compound having
one or more alicyclic structures (mainly 4- to 6-membered rings)
and two or more hydroxy groups per molecule. Examples of the
alicyclic diol (a1-2-2) include dihydric alcohols such as
1,4-cyclohexane dimethanol, tricyclodecanedimethanol, hydrogenated
bisphenol A, and hydrogenated bisphenol F; polylactone diols
obtained by adding lactones, such as s-caprolactone, to these
dihydric alcohols; etc. Such compounds can be used singly or in a
combination of two or more.
[0047] The aromatic diol (a1-2-3) is generally an aromatic compound
having two or more hydroxy groups per molecule. Examples of the
aromatic diol (a1-2-3) include ester diols such as
bis(hydroxyethyl)terephthalate; alkylene oxide adducts of bisphenol
A; and the like. Such compounds can be used singly or in a
combination of two or more.
[0048] Examples of the polyhydric alcohol other than the aliphatic
diol (a1-2-1), alicyclic diol (a1-2-2), and aromatic diol (a1-2-3)
include polyether diols such as polyethylene glycol, polypropylene
glycol, and polybutylene glycol; trihydric or higher alcohols such
as glycerol, trimethylolethane, trimethylolpropane, diglycerol,
triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol,
tris(2-hydroxyethyl)isocyanurate, sorbitol, and mannite;
polylactone polyols obtained by adding lactones, such as
.epsilon.-caprolactone, to these trihydric or higher hydric
alcohols; and the like.
[0049] Examples of the alcohol component (a1-2) other than the
above polyhydric alcohols include monohydric alcohols such as
methanol, ethanol, propyl alcohol, butyl alcohol, stearyl alcohol,
and 2-phenoxyethanol; alcohol compounds obtained by reacting acids
with monoepoxy compounds, such as propylene oxide, butylene oxide,
and a glycidyl ester of a synthetic highly branched saturated fatty
acid (trade name "Cardula E10", manufactured by HEXION Specialty
Chemicals); and the like.
[0050] From the viewpoint of the smoothness, distinctness of image,
water resistance, chipping resistance, etc. of the resulting
coating film, a polyester resin containing a C.sub.4 or higher
linear alkylene group in an amount of 0.3 to 2.5 mol/kg (on a resin
solids basis), and more preferably 0.6 to 2.0 mol/kg (on a resin
solids basis) is preferably used as the hydroxy-containing
polyester resin (A1-1).
[0051] The hydroxy-containing polyester resin containing a C.sub.4
or higher linear alkylene group can be produced, for example, by
using, as the acid component (a1-1), an aliphatic dicarboxylic acid
containing a C.sub.4 or higher linear alkylene group or using, as
the alcohol component (a1-2), an aliphatic diol containing a
C.sub.4 or higher linear alkylene group.
[0052] The "amount of C.sub.4 or higher linear alkylene group", as
used herein, is expressed by the number of moles of the C.sub.4 or
higher linear alkylene group per kg of the polyester resin (on a
solids basis). This can be calculated by dividing the total mole
number (Wm) of the C.sub.4 or higher linear alkylene
group-containing monomers used to produce a polyester resin by the
mass (Wr, unit: kg) of the obtained resin excluding the mass of
condensed water (i.e., Wm/Wr).
[0053] The "amount of the C.sub.4 or higher linear alkylene group"
can be controlled by adjusting the proportion of the C.sub.4 or
higher linear alkylene group-containing aliphatic dicarboxylic acid
and C.sub.4 or higher linear alkylene group-containing aliphatic
diol in the acid component (a1-1) and alcohol component (a1-2).
[0054] From the viewpoint of the smoothness, distinctness of image,
water resistance, chipping resistance, etc. of the resulting
coating film, the hydroxy-containing polyester resin (A1-1)
preferably contains a benzene ring and/or a cyclohexane ring in
such an amount that the total amount of benzene ring and
cyclohexane ring is in the range of 1.5 to 4.0 mol/kg (on a resin
solids basis), and more preferably 2.0 to 3.5 mol/kg (on a resin
solids basis).
[0055] The hydroxy-containing polyester resin containing a benzene
ring and/or a cyclohexane ring can be produced, for example, by
using, as the acid component (a1-1) or the alcohol component
(a1-2), at least one compound selected from the group consisting of
an alicyclic polybasic acid (a1-1-2), an aromatic polybasic acid
(a1-1-3), an alicyclic diol (a1-2-2), and an aromatic diol
(a1-2-3), and performing an esterification or transesterification
reaction.
[0056] The "total amount of benzene ring and cyclohexane ring" as
used herein refers to the total mole number of the benzene ring and
the cyclohexane ring contained per kg of the polyester resin (on a
solids basis). This can be calculated by dividing the total mole
number (Wn) of the benzene ring-containing monomers and cyclohexane
ring-containing monomers contained in monomers used to produce a
polyester resin by the mass (Wr, unit: kg) of the obtained resin
excluding the mass of condensed water (i.e., Wn/Wr).
[0057] The "total amount of benzene ring and cyclohexane ring" can
be controlled, for example, by adjusting the proportions of the
alicyclic polybasic acid (a1-1-2), aromatic polybasic acid
(a1-1-3), alicyclic diol (a1-2-2), and aromatic diol (a1-2-3) in
the acid component (a1-1) and alcohol component (a1-2).
[0058] The method of producing the hydroxy-containing polyester
resin (A1-1) is not particularly limited, and may be a commonly
used method. For example, a method can be employed in which the
acid component (a1-1) is reacted with the alcohol component (a1-2)
in a nitrogen stream at 150 to 250.degree. C. for 5 to 10 hours to
perform an esterification or transesterification reaction.
[0059] In the esterification or transesterification reaction, the
acid component (a1-1) and the alcohol component (a1-2) can be added
at once or in divided portions. A carboxy-containing polyester
resin may be first synthesized and then esterified with the alcohol
component (a1-2). Alternatively, the hydroxy-containing polyester
resin (A1-1) may be first synthesized and then reacted with an acid
anhydride to half-esterify the hydroxy-containing polyester
resin.
[0060] In the esterification or transesterification reaction, a
catalyst may be used to promote the reaction. Known catalysts are
usable including dibutyltin oxide, antimony trioxide, zinc acetate,
manganese acetate, cobalt acetate, calcium acetate, lead acetate,
tetrabutyl titanate, tetraisopropyl titanate, etc.
[0061] The hydroxy-containing polyester resin (A1-1) can be
modified with a fatty acid, a monoepoxy compound, a polyisocyanate
compound, or the like during the preparation of the resin or after
the esterification or transesterification reaction.
[0062] Examples of the fatty acid include palm oil fatty acid,
cottonseed oil fatty acid, hempseed oil fatty acid, rice bran oil
fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil
fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed
oil fatty acid, castor oil fatty acid, dehydrated castor oil fatty
acid, safflower oil fatty acid, and the like.
[0063] Preferable examples of the monoepoxy compound include a
glycidyl ester of a synthetic highly branched saturated fatty acid
(trade name "Cardura E10", a product of HEXION Specialty
Chemicals).
[0064] Examples of the polyisocyanate compound include aliphatic
diisocyanates such as lysine diisocyanate, hexamethylene
diisocyanate, and trimethylhexane diisocyanate; alicyclic
diisocyanates such as hydrogenated xylylene diisocyanate,
isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate,
methylcyclohexane-2,6-diisocyanate,
4,4'-methylenebis(cyclohexylisocyanate), and
1,3-(isocyanatomethyl)cyclohexane; aromatic diisocyanates such as
tolylene diisocyanate, xylylene diisocyanate, and diphenylmethane
diisocyanate; organic polyisocyanates such as lysine triisocyanate
and like tri- or higher polyisocyanates; adducts of such organic
polyisocyanates with polyhydric alcohols, low-molecular-weight
polyester resins, water or the like; cyclopolymers (e.g.,
isocyanurates), biuret-type adducts, etc., of such organic
diisocyanates; and the like. Such compounds can be used singly or
in a combination of two or more.
[0065] The hydroxy-containing polyester resin (A1-1) has a hydroxy
value of preferably about 10 to about 300 mg KOH/g, more preferably
about 50 to about 200 mg KOH/g, and even more preferably about 80
to about 180 mg KOH/g. The hydroxy-containing polyester resin
(A1-1) has an acid value of preferably about 3 to about 100 mg
KOH/g, more preferably about 5 to about 80 mg KOH/g, and even more
preferably about 10 to about 70 mg KOH/g.
[0066] The hydroxy-containing polyester resin (A1-1) has a weight
average molecular weight of preferably about 500 to about 50,000,
more preferably about 1,000 to about 30,000, and even more
preferably about 1,500 to about 20,000.
[0067] The hydroxy-containing polyester resin (A1-1) has a number
average molecular weight of preferably about 500 to about 5,000,
more preferably about 750 to about 4,000, and even more preferably
about 1,000 to about 3,000.
[0068] The number average molecular weight and weight average
molecular weight as used herein are determined by converting the
number average molecular weight and the weight average molecular
weight measured using a gel permeation chromatograph (GPC), based
on the molecular weight of polystyrene standards.
[0069] When the aqueous intermediate coating composition (X)
contains a hydroxy-containing polyester resin (A1-1) as the
hydroxy-containing resin (A1), the amount of hydroxy-containing
polyester resin (A1-1), on a solids basis, in the composition is
preferably about 5 to about 95 mass %, more preferably about 20 to
about 90 mass %, and even more preferably about 30 to about 85 mass
%, based on the total amount of hydroxy-containing resin (A1) and
polyisocyanate compound (B1), on a solids basis.
2) Hydroxy-Containing Acrylic Resin (A1-2)
[0070] The hydroxy-containing acrylic resin (A1-2) typically can be
produced by copolymerizing a hydroxy-containing polymerizable
unsaturated monomer (a1-3) and another polymerizable unsaturated
monomer (a1-4) that is copolymerizable with the hydroxy-containing
polymerizable unsaturated monomer (a1-3) by, for example, a known
method such as solution polymerization in an organic solvent,
emulsion polymerization in water, etc.
[0071] The hydroxy-containing polymerizable unsaturated monomer
(a1-3) is a compound having one or more hydroxy groups and one or
more polymerizable unsaturated bonds per molecule. Examples of the
hydroxy-containing polymerizable unsaturated monomer (a1-3) include
monoesters of (meth)acrylates with C.sub.2-8 dihydric alcohols,
such as 2-hydroxyethyl(meth)acrylate,
2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, and
4-hydroxybutyl(meth)acrylate; .epsilon.-caprolactone-modified
products of these monoesters; N-hydroxymethyl(meth)acrylamide;
allyl alcohol; (meth)acrylates having hydroxy-terminated
polyoxyethylene chains; and the like.
[0072] Examples of another polymerizable unsaturated monomer (a1-4)
that is copolymerizable with the hydroxy-containing polymerizable
unsaturated monomer (a1-3) include alkyl or
cycloalkyl(meth)acrylates such as methyl(meth)acrylate, ethyl
(meth)acrylate, n-propyl(meth)acrylate, i-propyl(meth)acrylate,
n-butyl(meth)acrylate, i-butyl(meth)acrylate, tert-butyl
(meth)acrylate, n-hexyl(meth)acrylate, n-octyl(meth)acrylate,
2-ethylhexyl(meth)acrylate, nonyl(meth)acrylate, tridecyl
(meth)acrylate, lauryl(meth)acrylate, stearyl(meth)acrylate,
"Isostearyl Acrylate" (trade name, a product of Osaka Organic
Chemical Industry Ltd.), cyclohexyl(meth)acrylate,
methylcyclohexyl(meth)acrylate, t-butylcyclohexyl(meth)acrylate,
and cyclododecyl(meth)acrylate; isobornyl group-containing
polymerizable unsaturated monomers such as isobornyl
(meth)acrylate; adamanthyl group-containing polymerizable
unsaturated monomers such as adamanthyl(meth)acrylate; vinyl
aromatic compounds such as styrene, .alpha.-methylstyrene, and
vinyltoluene; alkoxysilyl group-containing polymerizable
unsaturated monomers such as vinyltrimethoxysilane,
vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane,
.gamma.-(meth)acryloyloxypropyltrimethoxysilane, and .gamma.-(meth)
acryloyloxypropyltriethoxysilane; perfluoroalkyl (meth)acrylates
such as perfluorobutylethyl(meth)acrylate, and
perfluorooctylethyl(meth)acrylate; polymerizable unsaturated
monomers having fluorinated alkyl groups, such as fluoroolefins;
polymerizable unsaturated monomers having photopolymerizable
functional groups, such as a maleimide group; vinyl compounds such
as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl
propionate, and vinyl acetate; carboxy-containing polymerizable
unsaturated monomers, such as (meth)acrylic acid, maleic acid,
crotonic acid, and .beta.-carboxyethyl acrylate;
nitrogen-containing polymerizable unsaturated monomers, such as
(meth) acrylonitrile, (meth) acrylamide, N,N-dimethylaminoethyl
(meth)acrylate, N,N-dimethylaminopropyl(meth) acrylamide, and amine
adducts of glycidyl(meth)acrylate; polymerizable unsaturated
monomers having two or more polymerizable unsaturated groups per
molecule, such as allyl(meth)acrylate and 1,6-hexanediol
di(meth)acrylate; epoxy group-containing polymerizable unsaturated
monomers, such as glycidyl(meth)acrylate,
.beta.-methylglycidyl(meth)acrylate, 3,4-epoxycyclohexylmethyl
(meth)acrylate, 3,4-epoxycyclohexylethyl(meth)acrylate,
3,4-epoxycyclohexylpropyl(meth)acrylate, and allyl glycidyl ether;
(meth)acrylates having alkoxy-terminated polyoxyethylene chains;
sulfonic acid group-containing polymerizable unsaturated monomers,
such as 2-acrylamide-2-methylpropanesulfonic acid, allylsulfonic
acid, styrenesulfonic acid, and sulfoethyl methacrylate; sodium
salts and ammonium salts of these sulfonic acid group-containing
polymerizable unsaturated monomers; phosphoric acid
group-containing polymerizable unsaturated monomers, such as
2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid
phosphate, 2-acryloyloxypropyl acid phosphate, and
2-methacryloyloxypropyl acid phosphate; polymerizable unsaturated
monomers having UV-absorbing functional groups, such as
2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone,
2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone,
2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone,
2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, and
2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole;
UV-stable polymerizable unsaturated monomers such as 4-(meth)
acryloyloxy-1,2,2,6,6-pentamethylpiperidine,
4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine,
4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine,
1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine,
1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperid-
ine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine,
4-crotonoylamino-2,2,6,6-tetramethylpiperidine, and
1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine; carbonyl
group-containing polymerizable unsaturated monomers such as
acrolein, diacetone acrylamide, diacetone methacrylamide,
acetoacetoxylethyl methacrylate, formylstyrol, and vinyl alkyl
ketones having 4 to 7 carbon atoms (e.g, vinyl methyl ketone, vinyl
ethyl ketone, and vinyl butyl ketone); polymerizable unsaturated
monomers having cationic functional groups, such as tertiary amino
groups, and quaternary ammonium salt groups; and the like. Such
examples of the polymerizable unsaturated monomer (a1-4) can be
used singly or in a combination of two or more.
[0073] The hydroxy-containing acrylic resin (A1-2) may have a
cationic functional group. The hydroxy-containing acrylic resin
having a cationic functional group can be produced by, for example,
using a polymerizable unsaturated monomer having a cationic
functional group, such as a tertiary amino group or a quaternary
ammonium salt group, as at least a part of the above-mentioned
polymerizable unsaturated monomer (a1-4).
[0074] Examples of the tertiary amino group-containing
polymerizable unsaturated monomer include N,N-dimethylaminoethyl
(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate,
N,N-dimethylaminopropyl (meth)acrylate, N,N-di-t-butylaminoethyl
(meth)acrylate, N,N-dimethylaminobutyl(meth)acrylate, and like
N,N-dialkylaminoalkyl(meth)acrylates; N,N-dimethylaminoethyl (meth)
acrylamide, N,N-diethylaminoethyl(meth) acrylamide,
N,N-dimethylaminopropyl (meth)acrylamide, and like
N,N-dialkylaminoalkyl (meth)acrylamides; etc. Among these, it is
particularly preferable to use at least one selected from
N,N-dimethylaminoethyl(meth)acrylate and N,N-diethylaminoethyl
(meth)acrylate.
[0075] Examples of the quaternary ammonium salt group-containing
polymerizable unsaturated monomer include 2-(methacryloyloxy)ethyl
trimethyl ammonium chloride, 2-(methacryloyloxy)ethyl trimethyl
ammonium bromide, 2-(methacryloyloxy)ethyl trimethyl ammonium
dimethyl phosphate, and like (meth)acryloyloxyalkyl trialkyl
ammonium salts; methacryloylaminopropyltrimethylammonium chloride,
methacryloylaminopropyltrimethylammonium bromide, and like
(meth)acryloylaminoalkyltrialkylammonium salts; etc. Among these,
it is particularly preferable to use
2-(methacryloyloxy)ethyltrimethylammonium chloride.
[0076] From the viewpoint of the storage stability, the water
resistance of the resulting coating film, etc., the
hydroxy-containing acrylic resin (A1-2) preferably has a hydroxy
value of about 5 to about 300 mg KOH/g, more preferably about 15 to
about 200 mg KOH/g, and even more preferably about 30 to about 180
mg KOH/g.
[0077] When the hydroxy-containing acrylic resin (A1-2) has an acid
group such as a carboxy group, the hydroxy-containing acrylic resin
(A1-2) has an acid value of preferably about 3 to about 100 mg
KOH/g, more preferably about 5 to about 80 mg KOH/g, and even more
preferably about 10 to about 70 mg KOH/g, from the viewpoint of the
water resistance and other properties of the resulting coating
film.
[0078] The hydroxy-containing acrylic resin (A1-2) has a weight
average molecular weight of preferably about 2,000 to about
5,000,000, and more preferably about 3,000 to about 2,000,000.
[0079] When the aqueous intermediate coating composition (X) of the
present invention comprises the hydroxy-containing acrylic resin
(A1-2) as the hydroxy-containing resin (A1), the amount of
hydroxy-containing acrylic resin (A1-2), on a solids basis, in the
composition is preferably about 5 to about 95 mass %, more
preferably about 10 to about 70 mass %, and even more preferably
about 20 to about 50 mass %, based on the total amount of the
hydroxy-containing resin (A1) and the polyisocyanate compound (B1),
on a solids basis.
1.2.2 Carboxy-Containing Resin (A2)
[0080] The carboxy-containing resin (A2) contains at least one
carboxy group per molecule. From the viewpoint of the water
resistance and other properties of the resulting coating film, the
carboxy-containing resin (A2) has an acid value of preferably about
10 to about 100 mg KOH/g, more preferably about 15 to about 90 mg
KOH/g, and even more preferably about 15 to about 80 mg KOH/g.
[0081] The carboxy-containing resin (A2) can be made water soluble
or water dispersible by neutralizing the carboxy group with a basic
compound. Examples of the basic compound include those mentioned
above in Section 1.2.1 Hydroxy-containing resin (A1).
[0082] From the viewpoint of the water resistance and other
properties of the resulting coating film, the amount of basic
compound is preferably about 0.1 to about 1.5 equivalents, and more
preferably about 0.2 to about 1.2 equivalents, relative to the acid
groups of the carboxy-containing resin (A2).
[0083] When the carboxy-containing resin (A2) has a hydroxy group,
the carboxy-containing resin (A2) is a carboxy- and
hydroxy-containing resin (A3).
[0084] When the carboxy-containing resin (A2) has a hydroxy group,
the carboxy-containing resin (A2) has a hydroxy value of preferably
about 5 to about 200 mg KOH/g, more preferably about 15 to about
180 mg KOH/g, and even more preferably about 20 to about 160 mg
KOH/g, from the viewpoint of the water resistance, chipping
resistance, etc. of the resulting coating film.
[0085] Examples of the carboxy-containing resin (A2) include
polyester resins, acrylic resins, polyether resins, polycarbonate
resins, polyurethane resins, epoxy resins, alkyd resins, and the
like. Such resins can be used singly or in a combination of two or
more. It is particularly preferable to use, as the
carboxy-containing resin (A2), a carboxy-containing polyester resin
(A2-1) and/or a carboxy-containing acrylic resin (A2-2), and it is
more preferable to use a carboxy-containing polyester resin
(A2-1).
1) The Carboxy-Containing Polyester Resin (A2-1)
[0086] The carboxy-containing polyester resin (A2-1) can typically
be produced by an esterification or transesterification reaction of
an acid component (a1-1) with an alcohol component (a1-2).
[0087] A compound that is usually used as an acid component to
produce a polyester resin can be used as the acid component (a1-1).
Examples of the acid component (a1-1) include an aliphatic
polybasic acid (a1-1-1), an alicyclic polybasic acid (a1-1-2), an
aromatic polybasic acid (a1-1-3), and the like. Examples of the
aliphatic polybasic acid (a1-1-1), alicyclic polybasic acid
(a1-1-2), and aromatic polybasic acid (a1-1-3) include those
mentioned above in Section 1.2.1 Hydroxy-containing resin (A1).
From the viewpoint of the smoothness, distinctness of image, water
resistance, chipping resistance, etc. of the resulting coating
film, it is preferable to use, as the aliphatic polybasic acid
(a1-1-1), an aliphatic dicarboxylic acid containing a C.sub.4 or
higher linear alkylene group, preferably a C.sub.4-18, more
preferably C.sub.6-12 linear alkylene group.
[0088] It is particularly preferable to use, as the aromatic
polybasic acid (a1-1-3), phthalic acid, phthalic anhydride,
isophthalic acid, trimellitic acid, or trimellitic anhydride.
[0089] Examples of the acid component (a1-1) other than the
aliphatic polybasic acid (a1-1-1), alicyclic polybasic acid
(a1-1-2), and aromatic polybasic acid (a1-1-3) include those
mentioned above in Section 1.2.1 Hydroxy-containing resin (A1).
[0090] A polyhydric alcohol having two or more hydroxy groups per
molecule can be preferably used as the alcohol component (a1-2).
The polyhydric alcohol may be, for example, an aliphatic diols
(a1-2-1), an alicyclic diols (a1-2-2), an aromatic diols (a1-2-3),
etc. Examples of the aliphatic diol (a1-2-1), alicyclic diol
(a1-2-2), and aromatic diol (a1-2-3) include those mentioned above
in Section 1.2.1 Hydroxy-containing resin (A1).
[0091] From the viewpoint of the smoothness, distinctness of image,
chipping resistance, etc., of the resulting coating film, it is
preferable to use, as the aliphatic diol (a1-2-1), an aliphatic
diol containing a C.sub.4 or higher, preferably a C.sub.4-12, and
more preferably C.sub.6-10 linear alkylene group.
[0092] Examples of the polyhydric alcohol other than the aliphatic
diol (a1-2-1), alicyclic diol (a1-2-2), and aromatic diol (a1-2-3)
include those mentioned above in Section 1.2.1 Hydroxy-containing
resin (A1).
[0093] Examples of the alcohol component (a1-2) other than the
above-mentioned polyhydric alcohols include those mentioned above
in Section 1.2.1 Hydroxy-containing resin (A1).
[0094] From the viewpoint of the smoothness, distinctness of image,
water resistance, chipping resistance, etc., of the resulting
coating film, the carboxy-containing polyester resin (A2-1) is
preferably a polyester resin containing a C.sub.4 or higher linear
alkylene group in an amount of 0.3 to 2.5 mol/kg (on a resin solids
basis), and more preferably 0.6 to 2.0 mol/kg (on a resin solids
basis).
[0095] The carboxy-containing polyester resin containing C.sub.4 or
higher linear alkylene groups can be produced, for example, by
using an aliphatic dicarboxylic acid containing a C.sub.4 or higher
linear alkylene group as the acid component (a1-1) or using an
aliphatic diol containing a C.sub.4 or high linear alkylene group
as the alcohol component (a1-2).
[0096] The "amount of C.sub.4 or higher linear alkylene group" as
used herein refers to the number of moles of the C.sub.4 or higher
linear alkylene group contained per kg of the polyester resin (on a
solids basis). This can be calculated by dividing the total mole
number (Wm) of the C.sub.4 or higher linear alkylene
group-containing monomers used to produce a polyester resin by the
mass (Wr, unit: kg) of the obtained resin excluding the mass of
condensed water (i.e., Wm/Wr).
[0097] The "amount of C.sub.4 or higher linear alkylene group" can
be controlled by adjusting the proportions of the C.sub.4 or higher
linear alkylene group-containing aliphatic dicarboxylic acid and
C.sub.4 or higher linear alkylene group-containing aliphatic diol
in the acid component (a1-1) and alcohol component (a1-2).
[0098] From the viewpoint of the smoothness, distinctness of image,
water resistance, chipping resistance, etc., of the resulting
coating film, the carboxy-containing polyester resin (A2-1)
preferably contains a benzene ring and/or a cyclohexane ring in
such an amount that the total amount of benzene ring and
cyclohexane ring is the range of 1.5 to 4.0 mol/kg, and preferably
2.0 to 3.5 mol/kg (on a resin solids basis).
[0099] The carboxy-containing polyester resin having a benzene ring
and/or a cyclohexane ring can be produced, for example, by using,
as the acid component (a1-1) or alcohol component (a1-2), at least
one compound selected from the group consisting of an alicyclic
polybasic acid (a1-1-2), an aromatic polybasic acid (a1-1-3), an
alicyclic diol (a1-2-2), an aromatic diol (a1-2-3) and performing
an esterification or transesterification reaction.
[0100] The "total amount of benzene ring and cyclohexane ring", as
used herein, refers to the total mole number of the benzene ring
and cyclohexane ring contained per kg of the polyester resin (on a
solids basis). This can be calculated by dividing the total mole
number (Wn) of the benzene ring-containing monomers and cyclohexane
ring-containing monomers contained in monomers used to produce a
polyester resin by the mass (Wr, unit: kg) of the obtained resin
excluding the mass of condensed water (i.e., Wn/Wr).
[0101] The "total amount of benzene ring and cyclohexane ring" can
be controlled, for example, by adjusting the proportions of the
alicyclic polybasic acid (a1-1-2), aromatic polybasic acid
(a1-1-3), alicyclic diol (a1-2-2), and aromatic diol (a1-2-3) in
the acid component (a1-1) and alcohol component (a1-2).
[0102] The method for producing the carboxy-containing polyester
resin (A2-1) is not particularly limited, and may be a known
method. For example, a method can be employed in which the acid
component (a1-1) is reacted with the alcohol component (a1-2) in a
nitrogen stream at 150 to 250.degree. C. for 5 to 10 hours to
perform an esterification or transesterification reaction.
[0103] In the esterification or transesterification reaction, the
acid component (a1-1) and the alcohol component (a1-2) can be added
at once or in divided portions. A carboxy-containing polyester
resin (A2-1) may be first synthesized and then esterified with the
alcohol component (a1-2). Alternatively, the hydroxy-containing
polyester resin may be first synthesized and then reacted with an
acid anhydride to half-esterify the hydroxy-containing polyester
resin.
[0104] In the esterification or transesterification reaction, a
catalyst may be used to promote the reaction. Examples of the
catalyst include dibutyltin oxide, antimony trioxide, zinc acetate,
manganese acetate, cobalt acetate, calcium acetate, lead acetate,
tetrabutyl titanate, tetraisopropyl titanate, and like known
catalysts.
[0105] The carboxy-containing polyester resin (A2-1) can be
modified with a fatty acid, a monoepoxy compound, a polyisocyanate
compound, or the like during the preparation of the resin or after
the esterification or transesterification reaction.
[0106] Examples of the fatty acid, monoepoxy compound, and
polyisocyanate compound include those mentioned above in Section
1.2.1 Hydroxy-containing resin (A1).
[0107] The carboxy-containing resin (A2-1) preferably has an acid
value of about 10 to about 100 mg KOH/g, more preferably about 15
to about 90 mg KOH/g, and even more preferably about 15 to about 80
mg KOH/g.
[0108] The carboxy-containing polyester resin (A2-1) has a weight
average molecular weight of preferably about 500 to about 50,000,
more preferably about 1,000 to about 30,000, and even more
preferably about 1,500 to about 20,000.
[0109] The carboxy-containing polyester resin (A2-1) has a number
average molecular weight of preferably about 500 to about 5,000,
more preferably about 750 to about 4,000, and even more preferably
about 1,000 to about 3,000.
[0110] When the aqueous intermediate coating composition (X)
contains a carboxy-containing polyester resin (A2-1) as the
carboxy-containing resin (A2), the amount of carboxy-containing
polyester resin (A2-1), on a solids basis, in the composition is
preferably about 5 to about 95 mass %, more preferably about 20 to
about 90 mass %, and even more preferably about 30 to about 85 mass
%, based on the total amount of carboxy-containing resin (A2) and
polycarbodiimide compound (B2), on a solids basis.
2) Carboxy-Containing Acrylic Resin (A2-2)
[0111] The carboxy-containing acrylic resin (A2-2) can be typically
produced by copolymerizing a carboxy-containing polymerizable
unsaturated monomer (a2-1) and another polymerizable unsaturated
monomer (a2-2) that is copolymerizable with the carboxy-containing
polymerizable unsaturated monomer (a2-1) by, for example, a known
method such as solution polymerization in an organic solvent,
emulsion polymerization in water, etc.
[0112] The carboxy-containing polymerizable unsaturated monomer
(a2-1) is a compound having one or more carboxy groups and one or
more polymerizable unsaturated bonds per molecule. Examples of the
carboxy-containing polymerizable unsaturated monomers (a2-1)
include (meth)acrylic acid, maleic acid, crotonic acid,
.beta.-carboxyethyl acrylate, and the like. Such compounds can be
used singly or in a combination of two or more. It is particularly
preferable to use acrylic acid and/or methacrylic acid as the
carboxy-containing polymerizable unsaturated monomer (a2-1).
[0113] Examples of another polymerizable unsaturated monomer (a2-2)
that is copolymerizable with the carboxy-containing polymerizable
unsaturated monomer (a2-1) include alkyl or
cycloalkyl(meth)acrylates such as methyl(meth)acrylate, ethyl
(meth)acrylate, n-propyl(meth)acrylate, i-propyl(meth)acrylate,
n-butyl(meth)acrylate, i-butyl(meth)acrylate, tert-butyl
(meth)acrylate, n-hexyl(meth)acrylate, n-octyl(meth)acrylate,
2-ethylhexyl(meth)acrylate, nonyl(meth)acrylate, tridecyl
(meth)acrylate, lauryl(meth)acrylate, stearyl(meth)acrylate,
"Isostearyl Acrylate" (trade name, a product of Osaka Organic
Chemical Industry Ltd.), cyclohexyl(meth)acrylate,
methylcyclohexyl(meth)acrylate, t-butylcyclohexyl(meth)acrylate,
and cyclododecyl(meth)acrylate; hydroxy-containing polymerizable
unsaturated monomers such as 2-hydroxyethyl(meth)acrylate,
2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, and
4-hydroxybutyl(meth)acrylate, and like monoesters of
(meth)acrylates with C.sub.2-8 dihydric alcohols,
.epsilon.-caprolactone-modified products of these monoesters,
N-hydroxymethyl (meth)acrylamide, allyl alcohol, and
(meth)acrylates having hydroxy-terminated polyoxyethylene chains;
isobornyl group-containing polymerizable unsaturated monomers such
as isobornyl (meth)acrylate; adamanthyl group-containing
polymerizable unsaturated monomers such as
adamanthyl(meth)acrylate; vinyl aromatic compounds such as styrene,
.alpha.-methylstyrene, and vinyltoluene; alkoxysilyl
group-containing polymerizable unsaturated monomers such as
vinyltrimethoxysilane, vinyltriethoxysilane,
vinyltris(2-methoxyethoxy)silane, .gamma.-(meth)
acryloyloxypropyltrimethoxysilane, and
.gamma.-(meth)acryloyloxypropyltriethoxysilane; perfluoroalkyl
(meth)acrylates such as perfluorobutylethyl(meth)acrylate, and
perfluorooctylethyl(meth)acrylate; polymerizable unsaturated
monomers having fluorinated alkyl groups, such as fluoroolefins;
polymerizable unsaturated monomers having photopolymerizable
functional groups, such as a maleimide group; vinyl compounds such
as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl
propionate, and vinyl acetate; nitrogen-containing polymerizable
unsaturated monomers, such as (meth)acrylonitrile,
(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylate,
N,N-dimethylaminopropyl (meth) acrylamide, and amine adducts of
glycidyl(meth)acrylate; polymerizable unsaturated monomers having
two or more polymerizable unsaturated groups per molecule, such as
allyl(meth)acrylate and 1,6-hexanediol di(meth)acrylate; epoxy
group-containing polymerizable unsaturated monomers, such as
glycidyl(meth)acrylate, .beta.-methylglycidyl(meth)acrylate,
3,4-epoxycyclohexylmethyl(meth)acrylate,
3,4-epoxycyclohexylethyl(meth)acrylate,
3,4-epoxycyclohexylpropyl(meth)acrylate, and allyl glycidyl ether;
(meth)acrylates having alkoxy-terminated polyoxyethylene chains;
sulfonic acid group-containing polymerizable unsaturated monomers,
such as 2-acrylamide-2-methylpropanesulfonic acid, allylsulfonic
acid, styrenesulfonic acid, and sulfoethyl methacrylate; sodium
salts and ammonium salts of these sulfonic acid group-containing
polymerizable unsaturated monomers; phosphoric acid
group-containing polymerizable unsaturated monomers, such as
2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid
phosphate, 2-acryloyloxypropyl acid phosphate, and
2-methacryloyloxypropyl acid phosphate; polymerizable unsaturated
monomers having UV-absorbing functional groups, such as
2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone,
2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone,
2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone,
2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, and
2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole;
UV-stable polymerizable unsaturated monomers such as
4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine,
4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine,
4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine,
1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine,
1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperid-
ine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine,
4-crotonoylamino-2,2,6,6-tetramethylpiperidine, and
1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine; carbonyl
group-containing polymerizable unsaturated monomers such as
acrolein, diacetone acrylamide, diacetone methacrylamide,
acetoacetoxylethyl methacrylate, formylstyrol, and vinyl alkyl
ketones having 4 to 7 carbon atoms (e.g, vinyl methyl ketone, vinyl
ethyl ketone, and vinyl butyl ketone); polymerizable unsaturated
monomers having cationic functional groups, such as tertiary amino
groups, and quaternary ammonium salt groups; and the like. Such
examples of the polymerizable unsaturated monomer (a2-2) can be
used singly or in a combination of two or more.
[0114] The carboxy-containing acrylic resin (A2-2) may have a
cationic functional group. The carboxy-containing acrylic resin
having a cationic functional group can be produced by, for example,
using a polymerizable unsaturated monomer having a cationic
functional group, such as a tertiary amino group or a quaternary
ammonium salt group, as at least a part of the above-mentioned
polymerizable unsaturated monomer (a2-2).
[0115] Examples of the tertiary amino group-containing
polymerizable unsaturated monomer include N,N-dimethylaminoethyl
(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate,
N,N-dimethylaminopropyl (meth)acrylate, N,N-di-t-butylaminoethyl
(meth)acrylate, N,N-dimethylaminobutyl(meth)acrylate and like
N,N-dialkylaminoalkyl(meth)acrylates; N,N-dimethylaminoethyl (meth)
acrylamide, N,N-diethylaminoethyl(meth) acrylamide,
N,N-dimethylaminopropyl (meth)acrylamide and like
N,N-dialkylaminoalkyl (meth)acrylamides; etc. Among these, it is
preferable to use at least one member selected from
N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl
(meth)acrylate.
[0116] Examples of the quaternary ammonium salt group-containing
polymerizable unsaturated monomer include 2-(methacryloyloxy)ethyl
trimethyl ammonium chloride, 2-(methacryloyloxy)ethyl trimethyl
ammonium bromide, 2-(methacryloyloxy)ethyl trimethyl ammonium
dimethyl phosphate, and like (meth)acryloyloxyalkyl trialkyl
ammonium salts; methacryloylaminopropyltrimethylammonium chloride,
methacryloylaminopropyltrimethylammonium bromide, and like
(meth)acryloylaminoalkyltrialkylammonium salts; etc. Among these,
it is preferable to use 2-(methacryloyloxy)ethyltrimethylammonium
chloride.
[0117] From the viewpoint of the storage stability, water
resistance of the resulting coating film, etc., the
carboxy-containing acrylic resin (A2-2) has an acid value of
preferably about 10 to about 100 mg KOH/g, more preferably about 15
to about 90 mg KOH/g, and even more preferably about 15 to about 80
mg KOH/g.
[0118] The carboxy-containing acrylic resin (A2-2) has a weight
average molecular weight of preferably about 2,000 to about
5,000,000, and more preferably about 3,000 to about 2,000,000.
[0119] When the aqueous intermediate coating composition (X)
contains the carboxy-containing acrylic resin (A2-2) as the
carboxy-containing resin (A2), the amount of carboxy-containing
acrylic resin (A2-2), on a solids basis, in the composition is
preferably about 5 to about 95 mass %, more preferably about 10 to
about 70 mass %, and even more preferably about 20 to about 60 mass
%, based on the total amount of the carboxy-containing resin (A2)
and polycarbodiimide compound (B2), on a solids basis.
1.2.3 Carboxy- and Hydroxy-Containing Resin (A3)
[0120] The carboxy- and hydroxy-containing resin (A3) can be
produced by converting the carboxy-containing resin (A2) to have a
hydroxy group or by converting the hydroxy-containing resin (A1) to
have a carboxy group.
[0121] The carboxy- and hydroxy-containing resin (A3) preferably
has an acid value of 10 to 100 mg KOH/g, more preferably 15 to 90
mg KOH/g, and even more preferably 15 to 80 mg KOH/g, and
preferably has a hydroxy value of 5 to 200 mg KOH/g, more
preferably 15 to 180 mg KOH/g, and even more preferably 20 to 160
mg KOH/g.
[0122] It is preferable to use, as the carboxy- and
hydroxy-containing resin (A3), a carboxy- and hydroxy-containing
polyester resin (A3-1) and/or a carboxy- and hydroxy-containing
acrylic resin (A3-2). A carboxy- and hydroxy-containing polyester
resin (A3-1) is particularly preferable.
1) Carboxy- and Hydroxy-Containing Polyester Resin (A3-1)
[0123] The method for producing the carboxy- and hydroxy-containing
polyester resin (A3-1) is not particularly limited, and may be a
known method. For example, the resin (A3-1) can be produced by
adjusting the proportions of the acid component (a1-1) and alcohol
component (a1-2) or adjusting the reaction temperature and reaction
time in an esterification or transesterification reaction. The
following production methods can also be used for production. After
the carboxy-containing polyester resin (A2-1) is synthesized, a
portion of the carboxy groups in the carboxy-containing polyester
resin (A2-1) is esterified with the alcohol component (a1-2).
Alternatively, after the hydroxy-containing polyester resin (A1-1)
is synthesized, a portion of the hydroxy groups in the
hydroxy-containing polyester resin is half-esterified.
[0124] The carboxy- and hydroxy-containing polyester resin (A3-1)
preferably has an acid value of 10 to 100 mg KOH/g, more preferably
15 to 90 mg KOH/g, and even more preferably 15 to 80 mg KOH/g, and
preferably has a hydroxy value of 10 to 200 mg KOH/g, more
preferably 30 to 180 mg KOH/g, and even more preferably 40 to 160
mg KOH/g.
[0125] The carboxy- and hydroxy-containing polyester resin (A3-1)
has a weight average molecular weight of preferably about 500 to
about 50,000, more preferably about 1,000 to about 30,000, and even
more preferably about 1,500 to about 20,000.
[0126] The carboxy- and hydroxy-containing polyester resin (A3-1)
has a number average molecular weight of preferably about 500 to
about 5,000, more preferably about 750 to about 4,000, and even
more preferably about 1,000 to about 3,000.
2) Carboxy- and Hydroxy-Containing Acrylic Resin (A3-2)
[0127] The method for producing the carboxy- and hydroxy-containing
acrylic resin (A3-2) is not particularly limited, and may be a
known method. More specifically, the carboxy- and
hydroxy-containing acrylic resin (A3-2) can be produced, for
example, by using a hydroxy-containing polymerizable unsaturated
monomer as another polymerizable unsaturated monomers (a2-2) that
is copolymerizable with the carboxy-containing polymerizable
unsaturated monomer (a2-1).
[0128] Examples of the hydroxy-containing polymerizable unsaturated
monomer include monoesters of (meth)acrylates with C.sub.2-8
dihydric alcohols, such as 2-hydroxyethyl(meth)acrylate,
2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, and
4-hydroxybutyl(meth)acrylate; .epsilon.-caprolactone-modified
products of these monoesters; N-hydroxymethyl(meth)acrylamide;
allyl alcohol; (meth)acrylates having hydroxy-terminated
polyoxyethylene chains; and the like. Such compounds can be used
singly or in a combination of two or more.
[0129] The carboxy- and hydroxy-containing acrylic resin (A3-2)
preferably has an acid value of 10 to 100 mg KOH/g, more preferably
15 to 90 mg KOH/g, and even more preferably 15 to 80 mg KOH/g, and
preferably has a hydroxy value of 5 to 200 mg KOH/g, more
preferably 15 to 180 mg KOH/g, and even more preferably 20 to 160
mg KOH/g.
[0130] The carboxy- and hydroxy-containing acrylic resin (A3-2) has
a weight average molecular weight of preferably about 2,000 to
about 5,000,000, and more preferably about 3,000 to about
2,000,000.
1.3 Curing Agent (B)
[0131] The curing agent (B) used in the present invention is a
polyisocyanate compound (B1) and/or a polycarbodiimide compound
(B2), and can be selected according to the type of base resin (A)
used. For example, when the base resin (A) is a hydroxy-containing
resin (A1), a polyisocyanate compound (B1) is preferably used as
the curing agent (B). When the base resin (A) is a
carboxy-containing resin (A2), a polycarbodiimide compound (B2) is
preferably used. When the base resin (A) is a carboxy- and
hydroxy-containing resin (A3), the curing agent (B) is preferably a
polyisocyanate compound (B1) and/or a polycarbodiimide compound
(B2). When the curing agent (B) is a polycarbodiimide compound
(B2), the composition preferably further contains an amino resin
(B3).
[0132] The polyisocyanate compound (B1), polycarbodiimide compound
(B2), and amino resin (B3) are described below.
1.3.1 Polyisocyanate Compound (B1)
[0133] The polyisocyanate compound (B1) is a compound having two or
more unblocked isocyanate groups per molecule. Examples of such
compounds include aliphatic polyisocyanates, alicyclic
polyisocyanates, aromatic-aliphatic polyisocyanates, aromatic
polyisocyantates, derivatives thereof; and the like.
[0134] Examples of the aliphatic polyisocyanate include
trimethylene diisocyanate, tetramethylene diisocyanate,
hexamethylene diisocyanate, pentamethylene diisocyanate,
1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene
diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or
2,2,4-trimethylhexamethylene diisocyanate,
2,6-diisocyanatomethylcaproate, and like aliphatic diisocyanates;
lysine ester triisocyanate, 1,4,8-triisocyanatooctane,
1,6,11-triisocyanatoundecane,
1,8-diisocyanato-4-isocyanatomethyloctane,
1,3,6-triisocyanatohexane,
2,5,7-trimethyl-1,8-diisocyanate-5-isocyanatomethyloctane and like
aliphatic triisocyanates; and the like.
[0135] Examples of the alicyclic polyisocyanate include alicyclic
diisocyanates such as 1,3-cyclopentene diisocyanate,
1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate,
3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (common
name: isophorone diisocyanate), methyl-2,4-cyclohexane
diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or
1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated
xylylene diisocyanate), mixtures thereof, and norbornane
diisocyanate; alicyclic triisocyanates such as
1,3,5-triisocyanatocyclohexane,
1,3,5-trimethylisocyanatocyclohexane,
2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo2.2.1heptane,
2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo2.2.1heptane,
3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo2.2.1heptane,
5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo2.-
2.1heptane,
6-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo2.-
2.1heptane,
5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo2.-
2.1-heptane, and
6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo2.-
2.1heptane; and the like.
[0136] Examples of the aromatic-aliphatic polyisocyanate include
aromatic-aliphatic diisocyanates such as 1,3- or 1,4-xylylene
diisocyanate, mixtures thereof,
.omega.,.omega.'-diisocyanato-1,4-diethylbenzene, 1,3-, or
1,4-bis(1-isocyanato-1-methylethyl)benzene (common name:
tetramethylxylylene diisocyanate) or a mixture thereof;
aromatic-aliphatic triisocyanates such as
1,3,5-triisocyanatomethylbenzene; and the like.
[0137] Examples of the aromatic polyisocyanate include aromatic
diisocyanates such as m-phenylene diisocyanate, p-phenylene
diisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalene
diisocyanate, 2,4'- or 4,4'-diphenylmethane diisocyanate or a
mixture thereof, 2,4- or 2,6-tolylene diisocyanate or a mixture
thereof, 4,4'-toluidine diisocyanate and 4,4'-diphenylether
diisocyanate; aromatic triisocyanates such as
triphenylmethane-4,4',4''-triisocyanate,
1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; and
aromatic tetraisocyanates such as
4',4'-diphenylmethane-2,2',5,5'-tetraisocyanate; and the like.
[0138] Examples of the polyisocyanate derivative include dimers,
trimers, biurets, allophanates, urethodiones, urethoimines,
isocyanurates, oxadiazinetriones, polymethylene polyphenyl
polyisocyanates (crude MDI, polymeric MDI), crude TDI, or like
derivatives of the above-mentioned polyisocyanate compounds.
[0139] Such polyisocyanates and derivatives thereof can be used
singly or in a combination of two or more. It is particularly
preferable to use aliphatic diisocyanates, alicyclic diisocyanates,
and/or derivatives thereof singly or in a combination of two or
more.
[0140] From the viewpoint of the smoothness, etc. of the resulting
coating film, the polyisocyanate compound (B1) is preferably a
water-dispersible polyisocyanate compound. Any polyisocyanate
compound that can be stably dispersed in an aqueous medium can be
used as the water-dispersible polyisocyanate compound. It is
particularly preferable to use a hydrophilic polyisocyanate
compound (B1-1) produced by modifying a polyisocyanate compound to
impart hydrophilicity thereto and/or a water-dispersible
polyisocyanate compound prepared by mixing a polyisocyanate
compound (B1) with a surfactant.
[0141] Examples of the hydrophilic polyisocyanate compound (B1-1)
include anionic hydrophilic polyisocyanate compounds (B1-1-1)
obtained by reacting an isocyanate group of a polyisocyanate
compound with an active hydrogen group of an active hydrogen
group-containing compound having an anionic group; nonionic
hydrophilic polyisocyanate compounds (B1-1-2) obtained by reacting
a hydrophilic polyether alcohol such as a monoalcohol of
polyoxyethylene with a polyisocyanate compound; and the like. Such
compounds can be used singly or in a combination of two or
more.
[0142] Examples of the active hydrogen group-containing compound
having an anionic group include compounds having an anionic group
such as a carboxyl group, a sulfonic acid group, a phosphoric acid
group or a betaine structure-containing group, and also having an
active hydrogen group that can react with an isocyanate group, such
as a hydroxy group or an amino group.
[0143] The active hydrogen group-containing compound having an
anionic group is not particularly limited. Examples thereof include
compounds having one anionic group and at least two active hydrogen
groups. More specifically, examples of the active hydrogen
group-containing compound having a carboxyl group include
dihydroxycarboxylic acids such as 2,2-dimethylolacetic acid,
2,2-dimethylollactic acid, 2,2-dimethylolpropionic acid,
2,2-dimethylolbutanoic acid, dimethylolheptanoic acid,
dimethylolnonanoic acid, 2,2-dimethylolbutyric acid, and
2,2-dimethylolvaleric acid; diaminocarboxylic acids such as
1-carboxy-1,5-pentylenediamine, dihydroxybenzoic acid,
3,5-diaminobenzoic acid, lysine, and alginine; half-ester compounds
of polyoxypropylene triol with maleic anhydride or phthalic
anhydride; and the like.
[0144] Examples of the active hydrogen group-containing compound
having a sulfonic acid group include
N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid,
1,3-phenylenediamine-4,6-disulfonic acid, diaminobutanesulfonic
acid, 3,6-diamino-2-toluenesulfonic acid,
2,4-diamino-5-toluenesulfonic acid,
2-(cyclohexylamino)-ethanesulfonic acid,
3-(cyclohexylamino)-propanesulfonic acid, and the like.
[0145] Examples of the active hydrogen group-containing compound
having a phosphoric acid group include 2,3-dihydroxypropylphenyl
phosphate and the like.
[0146] Examples of the active hydrogen group-containing compound
having a betaine structure-containing group include sulfobetaine
group-containing compounds obtained by reacting a tertiary amine
such as N-methyldiethanolamine with 1,3-propanesultone.
[0147] These active hydrogen group-containing compounds having
anionic groups may be converted to alkylene oxide modified products
by the addition of an alkylene oxide, such as ethylene oxide or
propylene oxide.
[0148] Such active hydrogen group-containing compounds having an
anionic group can be used singly or in a combination of two or
more.
[0149] From the viewpoint of smoothness of the resulting coating
film, it is particularly preferable to use, as the anionic
hydrophilic polyisocyanate compound (B1-1-1), an anionic
hydrophilic polyisocyanate compound obtained by reacting an
isocyanate group of a polyisocyanate compound with an active
hydrogen group of an active hydrogen group-containing compound
having sulfonic acid group and/or phosphoric acid group.
[0150] Examples of the polyisocyanate compound that can be
converted to a hydrophilic modified polyisocyanate compound (B1-1)
include those already mentioned above. Among these compounds,
aliphatic diisocyanates, alicyclic diisocyanates, and derivatives
thereof are preferable. Specific examples of preferable compounds
include hexamethylene diisocyanate (HMDI), derivatives of
hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI)
and derivatives of isophorone diisocyanate (IPDI).
[0151] When water dispersibility is imparted by mixing a
polyisocyanate compound (B1) with a surfactant beforehand, an
anionic surfactant and/or a nonionic surfactant is preferably used
as the surfactant, and an anionic surfactant is particularly
preferable.
[0152] From the viewpoint of water resistance of the resulting
coating film, it is usually preferable to use the polyisocyanate
compound (B1) in a proportion such that the equivalent ratio
(NCO/OH) of the isocyanate group in the polyisocyanate compound
(B1) to the hydroxy group in the hydroxyl-containing resin (A1) is
in the range of 0.5 to 2.0, and particularly 0.8 to 1.5.
1.3.2 Polycarbodiimide Compound (B2)
[0153] The polycarbodiimide compound (B2) is a compound having at
least two carbodiimide groups per molecule. Examples of such
compounds include those obtained by subjecting isocyanate groups of
an isocyanate group-containing compound to a carbon dioxide removal
reaction with each other.
[0154] From the viewpoint of the smoothness and other properties of
the resulting coating film, it is preferable to use a water-soluble
or water-dispersible polycarbodiimide compound as the
polycarbodiimide compound (B2). Any polycarbodiimide compound that
can be stably dissolved or dispersed in an aqueous medium can be
used as the water-soluble or water-dispersible polycarbodiimide
compound.
[0155] Examples of the water-soluble polycarbodiimide compound
include "Carbodilite SV-02", "Carbodilite V-02", "Carbodilite
V-02-L2", "Carbodilite V-04" (products of Nisshinbo Industries,
Inc., trade names), and the like. Examples of the water-dispersible
polycarbodiimide compound include "Carbodilite E-01" and
"Carbodilite E-02" (products of Nisshinbo Industries, Inc., trade
names).
[0156] Such polycarbodiimide compounds (B2) can be used singly or
in a combination of two or more.
1.3.3 Amino Resin (B3)
[0157] Examples of the amino resin (B3) include partially or fully
methylolated amino resins obtained by reacting amino components
with aldehyde components.
[0158] Examples of the amino components include melamine, urea,
benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine,
dicyandiamide, and the like. Examples of the aldehyde components
include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde,
and the like.
[0159] Also usable are products obtained by partially or fully
etherifying, with suitable alcohols, the methylol groups of
partially or fully methylolated amino resins. Examples of alcohols
that can be used for etherification include methyl alcohol, ethyl
alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol,
i-butyl alcohol, 2-ethyl-1-butanol, 2-ethyl-1-hexanol, and the
like.
[0160] The amino resin (B3) is preferably a melamine resin (B3-1).
Examples of the melamine resin (B3-1) include alkyl-etherified
melamine resins, which are obtained by partially or fully
etherifying, with suitable alcohols, methylol groups of partially
or fully methylolated melamine resins.
[0161] Examples of alkyl-etherified melamine resins preferably used
include methyl etherified melamine resins obtained by partially or
fully etherifying, with methyl alcohol, methylol groups of
partially or fully methylolated melamine resins; butyl-etherified
melamine resins obtained by partially or fully etherifying, with
butyl alcohol, methylol groups of partially or fully methylolated
melamine resins; and methyl-butyl mixed etherified melamine resins
obtained by partially or fully etherifying, with methyl alcohol and
butyl alcohol, methylol groups of partially or fully methylolated
melamine resins. Among these, methyl etherified melamine resins and
methyl-butyl mixed etherified melamine resins are preferable, and
methyl-butyl mixed etherified melamine resins are particularly
preferable from the viewpoint of the smoothness, distinctness of
image, water resistance, etc., of the resulting multilayer coating
film.
[0162] From the viewpoint of the smoothness, distinctness of image,
water resistance, etc., of the resulting multilayer coating film,
the methyl-butyl mixed etherified melamine resin preferably has a
methoxy/butoxy molar ratio in the range of 90/10 to 50/50, and
preferably 80/20 to 60/40.
[0163] The melamine resin (B3-1) preferably has a weight average
molecular weight of 400 to 6,000, preferably 500 to 4,000, and even
more preferably 600 to 2,000.
[0164] Commercially available products can be used as the melamine
resin (B3-1). Trade names of commercial products of such melamine
resins include, for example, "Cymel 202", "Cymel 203", "Cymel 204",
"Cymel 211", "Cymel 238", "Cymel 251", "Cymel 303", "Cymel 323",
"Cymel 324", "Cymel 325", "Cymel 327", "Cymel 350", "Cymel 385",
"Cymel 1156", "Cymel 1158", "Cymel 1116", "Cymel 1130" (products of
Nihon Cytec Industries Inc.); and "U-Van 120", "U-Van 20HS", "U-Van
20SE60", "U-Van 2021", "U-Van 2028", "U-Van 28-60" (products of
Mitsui Chemicals, Inc.); and the like.
[0165] When the aqueous intermediate coating composition (X)
contains the melamine resin (B3-1), a catalyst can be used.
Examples of usable catalysts include sulfonic acids such as
p-toluenesulfonic acid, dodecylbenzenesulfonic acid, and
dinonylnaphthalene sulfonic acid; and salts obtained by
neutralizing such sulfonic acids with amines; salts obtained by
neutralizing phosphoric ester compounds with amines; and the
like.
1.4 Diester Compound (C)
[0166] The diester compound (C) is represented by formula (1):
##STR00005##
(wherein R.sup.1 and R.sup.2 are each independently a hydrocarbon
group having 4 to 18 carbon atoms, R.sup.3 is an alkylene group
having 2 to 4 carbon atoms, m is an integer of 3 to 25, and m
oxyalkylene units (R.sup.3--O) may be the same or different).
[0167] From the viewpoint of the smoothness, distinctness of image,
water resistance, flip-flop effect, and suppression of metallic
mottling of the resulting coating film, the carbon number of each
of R.sup.1 and R.sup.2 in Formula (1) is preferably 4 to 18, more
preferably 5 to 11, even more preferably 5 to 9, and still more
preferably 6 to 8. R.sup.1 and R.sup.2 are preferably straight- or
branched-chain alkyl groups, and more preferably branched-chain
alkyl groups. It is particularly preferable that R.sup.1 and
R.sup.2 be C.sub.6-8 branched-chain alkyl groups. When R.sup.1 and
R.sup.2 are branched-chain alkyl groups, the composition of the
present invention is capable of forming a multilayer coating film
having excellent appearance in which the smoothness and flip-flop
effect are excellent and metallic mottling is suppressed, even if
the composition is applied after relatively long-term storage.
[0168] From the viewpoint of the smoothness, distinctness of image,
flip-flop effect, and suppression of metallic mottling, of the
resulting multilayer coating film, R.sup.3 in the above Formula (1)
is preferably a C.sub.2 or C.sub.3 alkylene group, and more
preferably a C.sub.2 alkylene group (ethylene group). From the
viewpoint of the smoothness, distinctness of image, water
resistance, flip-flop effect, and suppression of metallic mottling,
m in Formula (1) is preferably 4 to 12, and more preferably 6 to
9.
[0169] The diester compound (C) has a molecular weight of
preferably about 320 to about 1,400, more preferably about 450 to
about 1,000, even more preferably about 500 to about 800, and still
more preferably about 500 to about 700.
[0170] The diester compound (C) is preferably a diester compound of
a polyoxyalkylene glycol with an aliphatic monocarboxylic acid.
Specifically, the diester compound (C) can be obtained by, for
example, an esterification reaction of a polyoxyalkylene glycol
having two terminal hydroxy groups with a monocarboxylic acid
having a C.sub.4-18 hydrocarbon group.
[0171] Examples of the polyoxyalkylene glycol include polyethylene
glycol, polypropylene glycol, copolymers of polyethylene and
propylene glycol, polybutylene glycol, etc. Among these, it is
particularly preferable to use polyethylene glycol. The
polyoxyalkylene glycol has a number average molecular weight of
preferably about 100 to about 1,200, more preferably about 150 to
about 600, and even more preferably about 200 to about 400.
[0172] Examples of the monocarboxylic acid having a C.sub.4-18
hydrocarbon group include pentanoic acid, hexanoic acid,
2-ethylbutanoic acid, 3-methylpentanoic acid, benzoic acid,
cyclohexanecarboxylic acid, heptanoic acid, 2-ethylpentanoic acid,
3-ethylpentanoic acid, octanoic acid, 2-ethylhexanoic acid,
4-ethylhexanoic acid, nonanoic acid, 2-ethylheptanoic acid,
decanoic acid, 2-ethyloctanoic acid, 4-ethyloctanoic acid,
dodecanoic acid, hexadecanoic acid, octadecanoic acid, and the
like. Among these, monocarboxylic acids having C.sub.5-9 alkyl
groups, such as hexanoic acid, heptanoic acid, 2-ethylpentanoic
acid, 3-ethylpentanoic acid, octanoic acid, 2-ethylhexanoic acid,
4-ethylhexanoic acid, nonanoic acid, 2-ethylheptanoic acid,
decanoic acid, 2-ethyloctanoic acid, and 4-ethyloctanoic acid, are
preferable; monocarboxylic acids having C.sub.6-8 alkyl groups,
such as heptanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic
acid, octanoic acid, 2-ethylhexanoic acid, 4-ethylhexanoic acid,
nonanoic acid, and 2-ethylheptanoic acid, are more preferable; and
monocarboxylic acid having C.sub.6-8 branched-chain alkyl groups,
such as 2-ethylpentanoic acid, 3-ethylpentanoic acid,
2-ethylhexanoic acid, 4-ethylhexanoic acid, and 2-ethylheptanoic
acid, are still more preferable.
[0173] These polyoxyalkylene glycols and monocarboxylic acids can
be used singly or in a combination of two or more.
[0174] The diesterification reaction of the polyoxyalkylene glycol
with the monocarboxylic acid having a C.sub.4-18 hydrocarbon group
can be carried out by a known method.
[0175] A multilayer coating film with excellent smoothness and high
distinctness of image can be formed by using the aqueous
intermediate coating composition (X) containing a base resin (A), a
curing agent (B), and a diester compound (C) in a 3-coat 1-bake
process comprising successively applying an aqueous intermediate
coating composition, an aqueous base coating composition, and a
clear coating composition and simultaneously heat-curing the
resulting three coating layers to form a multilayer coating film.
This is presumably for the following reason.
[0176] Application of the aqueous intermediate coating composition
(X) containing a diester compound (C) forms an intermediate coating
layer having appropriate hydrophilicity. Accordingly, the aqueous
base coating composition (Y) applied to the intermediate coating
layer uniformly spreads in a wet state over the intermediate
coating layer, thus forming a multilayer coating film with
excellent smoothness. Moreover, curing of the intermediate coating
layer, which occurs in a relatively early stage of the heating step
due to a relatively high reactivity between the base resin (A) and
the curing agent (B) in the aqueous intermediate coating
composition (X), inhibits the formation of a mixed layer of the
intermediate coating with the aqueous base coating composition (Y)
used to form an upper layer, thus enhancing the distinctness of
image; furthermore, the presence of the diester compound (C)
diminishes the reduction of thermal flowability of the coating
caused by a rapid curing reaction between the base resin (A) and
the curing agent (B), thus proving a multilayer coating film with
excellent smoothness.
1.5 Aqueous Intermediate Coating Composition (X)
[0177] The aqueous intermediate coating composition (X) used in the
method for forming a multilayer coating film of the present
invention is an aqueous coating composition comprising a base resin
(A), a curing agent (B) (a polyisocyanate compound (B1) and/or a
polycarbodiimide compound (B2)), and a diester compound (C).
[0178] The "aqueous coating composition" as used herein is a term
used in contrast with an "organic solvent-based coating
composition", and generally means a coating composition produced by
dispersing or dissolving a coating film-forming resin, a pigment,
etc., in water or in a medium mainly consisting of water (aqueous
medium). The amount of water in the aqueous intermediate coating
composition (X) is preferably about 10 to about 90 mass %, more
preferably about 20 to about 80 mass %, and even more preferably
about 30 to about 60 mass %.
[0179] The proportions of the base resin (A), curing agent (B), and
diester compound (C) in the aqueous intermediate coating
composition (X) are preferably within the following ranges, based
on 100 parts by mass of the total solids content of the base resin
(A) and the curing agent (B):
the amount of base resin (A) is 30 to 95 parts by mass, more
preferably 50 to 90 parts by mass, and even more preferably 60 to
85 parts by mass; the amount of curing agent (B) is 5 to 70 parts
by mass, more preferably 10 to 50 parts by mass, and even more
preferably 15 to 40 parts by mass; and the amount of diester
compound (C) is 1 to 30 parts by mass, more preferably 3 to 20
parts by mass, and even more preferably 5 to 15 parts by mass.
[0180] The above proportions can be used for any of the following
combinations of the components: [0181] (1) a combination wherein
the base resin (A) is a hydroxy-containing resin (A1) and the
curing agent (B) is a polyisocyanate compound (B1); [0182] (2) a
combination wherein the base resin (A) is a carboxy-containing
resin (A2) and the curing agent (B) is a polycarbodiimide compound
(B2); [0183] (3) a combination wherein the base resin (A) is a
carboxy- and hydroxy-containing resin (A3) and the curing agent (B)
is a polyisocyanate compound (B1) and/or polycarbodiimide compound
(B2); and [0184] (4) a combination wherein the base resin (A) is a
carboxy- and hydroxy-containing resin (A3) and the curing agent (B)
is a polycarbodiimide compound (B2) and an amino resin (B3).
[0185] Various compositions described below comprise base resin (A)
and curing agent (B) as basic components. The combination of base
resin (A) and curing agent (B) in the compositions below can be
selected from the combinations of base resin (A) and curing agent
(B) shown above in (1) to (4).
[0186] From the viewpoint of the smoothness, distinctness of image,
water resistance, chipping resistance, etc. of the resulting
multilayer coating film, the aqueous intermediate coating
composition (X) of the present invention preferably contains a
carboxy- and hydroxy-containing resin (A3) as the base resin (A),
and an amino resin as the curing agent (B). Examples of the amino
resin are the same as mentioned above.
[0187] When the aqueous intermediate coating composition (X)
contains a carboxy- and hydroxy-containing resin (A3) and a
melamine resin (B3-1), the proportions of the carboxy- and
hydroxy-containing resin (A3), polycarbodiimide compound (B2),
diester compound (C), and melamine resin (B3-1) in the composition
(X) are preferably within the following ranges, per 100 parts by
mass of the total amount of carboxy- and hydroxy-containing resin
(A3) and the polycarbodiimide compound (B2), on a solids basis:
the amount of carboxy- and hydroxy-containing resin (A3) is 30 to
95 parts by mass, preferably 50 to 90 parts by mass, and more
preferably 60 to 85 parts by mass; the amount of polycarbodiimide
compound (B2) is 5 to 70 parts by mass, preferably 10 to 50 parts
by mass, and even more preferably 15 to 40 parts by mass; the
amount of diester compound (C) is 1 to 30 parts by mass, preferably
3 to 20 parts by mass, and even more preferably 5 to 15 parts by
mass; and the amount of melamine resin (B3-1) is 5 to 70 parts by
mass, preferably 10 to 50 parts by mass, and even more preferably
15 to 40 parts by mass.
[0188] The aqueous intermediate coating composition (X) may
contain, in addition to the base resin (A), a resin for
modification that is substantially free of hydroxy groups and/or
carboxy groups. Examples of the resin for modification include
water soluble- or water dispersible-, polyurethane resins,
polyester resins, acrylic resins, alkyd resins, silicon resins,
fluororesins, epoxy resins, and the like.
[0189] When the aqueous intermediate coating composition (X)
contains such a resin for modification, the amount of the resin for
modification is typically 1 to 50 parts by mass, preferably 3 to 40
parts by mass, and even more preferably 5 to 30 parts by mass, per
100 parts by mass of the total amount of base resin (A) and curing
agent (B), on a solids basis.
[0190] From the viewpoint of the chipping resistance, it is
preferable to use a polyurethane resin as the resin for
modification. Examples of the polyurethane resin include a resin
prepared as follows: a urethane prepolymer is produced by reacting
at least one diol selected from the group consisting of
polyetherdiols, polyesterdiols and polycarbonate diols, a
low-molecular-weight polyhydroxy compound and dimethanol alkanoic
acid with aliphatic and/or alicyclic diisocyanates; the urethane
prepolymer is neutralized with a tertiary amine and emulsified and
dispersed in water; and if necessary, the resulting emulsion is
mixed with an aqueous medium containing a chain extender such as a
polyamine, a crosslinking agent, and/or a terminator, to perform a
reaction until substantially no isocyanate group remains. The above
method usually yields a self-emulsifiable urethane emulsion with a
mean particle diameter of about 0.001 to about 3 .mu.m. Examples of
commercial products of the urethane resin include "U-Coat UX-5000"
and "U-Coat UX-8100" (trade names, products of Sanyo Chemical
Industries, Ltd.), etc.
[0191] When the aqueous intermediate coating composition (X)
contains a polyurethane resin as mentioned above, the amount of
polyurethane resin is generally 1 to 50 parts by mass, preferably 3
to 40 parts by mass, and more preferably 5 to 30 parts by mass, per
100 parts by mass of the total amount of base resin (A) and curing
agent (B) in the aqueous intermediate coating composition (X), on a
solids basis.
[0192] When the hydroxy-containing resin (A1) and/or the resin for
modification in the aqueous intermediate coating composition (X) of
the present invention has one or more reactive functional groups
other than hydroxy groups, the composition (X) may contain a
compound that is reactive with the reactive functional groups. More
specifically, for example, when the hydroxy-containing resin (A1)
and/or the resin for modification has a carboxy group, the aqueous
intermediate coating composition (X) may contain a carbodiimide
group-containing compound.
[0193] Examples of the carbodiimide group-containing compound
include those obtained by subjecting isocyanate groups of the
isocyanate group-containing compound (B1) to a carbon dioxide
removal reaction with each other. The polycarbodiimide compound
(B2) can also be preferably used. Commercially available products
can also be used as the carbodiimide group-containing compound.
Examples of commercial products of such carbodiimide
group-containing compounds include "Carbodilite SV-02",
"Carbodilite V-02", "Carbodilite V-02-L2", "Carbodilite V-04",
"Carbodilite E-01", and "Carbodilite E-02" (products of Nisshinbo
Industries, Inc., trade names), etc.
[0194] When the carboxy-containing resin (A2) and/or the resin for
modification in the aqueous intermediate coating composition (X) of
the present invention have one or more reactive functional groups
other than carboxy groups, the composition (X) may contain a
compound that is reactive with the reactive functional groups. More
specifically, for example, when the carboxy-containing resin (A2)
and/or the resin for modification has a hydroxy group, the aqueous
intermediate coating composition (X) may contain an amino resin, a
polyisocyanate compound, a blocked polyisocyanate compound,
etc.
[0195] Examples of the amino resin and the polyisocyanate compound
include those mentioned above.
[0196] The blocked polyisocyanate compound is a compound having at
least two isocyanate groups per molecule wherein the isocyanate
groups are blocked by a blocking agent.
[0197] Examples of the blocking agent include phenol compounds such
as phenol, cresol, xylenol, nitrophenol, ethylphenol,
hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol,
octylphenol, and methyl hydroxybenzonate; lactam compounds such as
.epsilon.-caprolactam, .delta.-valerolactam, .gamma.-butyrolactam,
and .beta.-propiolactam; aliphatic alcohol compounds such as
methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, and
lauryl alcohol; ether compounds such as ethylene glycol monomethyl
ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl
ether, diethylene glycol monomethyl ether, diethylene glycol
monoethyl ether, propylene glycol monomethyl ether, and
methoxymethanol; alcohol compounds such as benzyl alcohol, glycolic
acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic
acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea,
methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, and
2-hydroxyethyl methacrylate; oxime compounds such as formamidoxime,
acetamidooxime, acetoxime, methyl ethyl ketoxime, diacetylmonoxime,
benzophenone oxime, and cyclohexane oxime; active methylene
compounds such as dimethyl malonate, diethyl malonate, ethyl
acetoacetate, methyl acetoacetate, and acetylacetone; mercaptan
compounds such as butyl mercaptan, t-butyl mercaptan, hexyl
mercaptan, t-dodecyl mercaptan, 2-mercapto benzo thiazole,
thiophenol, methylthiophenol, and ethylthiophenol; acid amide
compounds such as acetanilide, acetanisidide, acetotoluide,
acrylamide, methacrylamide, acetamide, stearic acid amide, and
benzamide; imide compounds such as succinimide, phthalimide, and
maleinimide; amine compounds such as diphenylamine,
phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole,
aniline, naphthylamine, butylamine, dibutylamine, and butylphenyl
amine; imidazole compounds such as imidazole and 2-ethylimidazole;
urea compounds such as urea, thiourea, ethyleneurea,
ethylenetiourea, and diphenylurea; carbamate compounds such as
phenyl N-phenylcarbamate; imine compounds such as ethyleneimine and
propyleneimine; sulfite compounds such as sodium bisulfite and
potassium bisulfite; azole compounds; and the like. Examples of
such azole compounds include pyrazole or pyrazole derivatives such
as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole,
4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole,
4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole;
imidazole or imidazole derivatives such as imidazole,
benzimidazole, 2-methylimidazole, 2-ethylimidazole, and
2-phenylimidazole; imidazoline derivatives such as
2-methylimidazoline and 2-phenylimidazoline; and the like.
1.5.1 Pigment (D)
[0198] The aqueous intermediate coating composition (X) preferably
contains a pigment (D). Examples of the pigment (D) include
coloring pigments (D1), extender pigments (D2), luster pigments
(D3), and the like. Such pigments can be used singly or in a
combination of two or more.
[0199] When the aqueous intermediate coating composition (X)
contains a pigment (D), the amount of pigment (D) in the aqueous
intermediate coating composition (X) is generally 1 to 200 parts by
mass, preferably 20 to 150 parts by mass, and more preferably 50 to
120 parts by mass, per 100 parts by mass of the total amount of
base resin (A) and curing agent (B), on a solids basis.
[0200] It is particularly preferable that the aqueous intermediate
coating composition (X) contains a coloring pigment (D1) and/or an
extender pigment (D2) in such an amount that the total amount of
coloring pigment (D1) and extender pigment (D2) is 40 to 180 parts
by mass, preferably 50 to 160 parts by mass, and more preferably 60
to 140 parts by mass, per 100 parts by mass of the total amount of
base resin (A) and curing agent (B) in the aqueous intermediate
coating composition (X), on a solids basis.
[0201] Examples of the coloring pigment (D1) include titanium
oxide, zinc flower, carbon black, molybdenum red, Prussian blue,
cobalt blue, azo pigments, phthalocyanine pigments, quinacridone
pigments, isoindoline pigments, threne pigments, perylene pigments,
dioxazine pigments, diketopyrrolopyrrole pigments, and the like.
Among these, titanium oxide and carbon black are preferable.
[0202] When the aqueous intermediate coating composition (X)
contains a coloring pigment (D1) as described above, the amount of
coloring pigment (D1) is typically 1 to 180 parts by mass,
preferably 3 to 160 parts by mass, and even more preferably 5 to
140 parts by mass, per 100 parts by mass of the total amount of
base resin (A) and curing agent (B) in the aqueous intermediate
coating composition (X), on a solids basis.
[0203] Examples of the extender pigment (D2) include clay, kaolin,
barium sulfate, barium carbonate, calcium carbonate, talc, silica,
alumina white, etc. Among these, barium sulfate and talc are
preferable.
[0204] It is particularly preferable to use, as the extender
pigment (D2), barium sulfate having a mean primary particle
diameter of 1 .mu.m or less, more preferably 0.01 to 0.8 .mu.m. The
aqueous intermediate coating composition (X) containing such barium
sulfate as the extender pigment (D2) can form a multilayer coating
film that has an excellent appearance with excellent smoothness,
and also with a high flip-flop effect and little metallic mottling,
when the aqueous base coating composition (Y) described below
contains a luster pigment (D3).
[0205] The mean primary particle diameter of barium sulfate as used
herein is determined by observing barium sulfate using a scanning
electron microscope and averaging the maximum diameters of 20
barium sulfate particles on a straight line drawn at random on the
electron microscope photograph.
[0206] When the aqueous intermediate coating composition (X)
contains an extender pigment (D2) as described above, the amount of
extender pigment (D2) is typically 1 to 150 parts by mass,
preferably 5 to 130 parts by mass, and even more preferably 10 to
110 parts by mass, per 100 parts by mass of the total amount of
base resin (A) and curing agent (B) in the aqueous intermediate
coating composition (X), on a solids basis.
[0207] Examples of the luster pigment (D3) include aluminium (which
may be vapor-deposited aluminum), copper, zinc, brass, nickel,
aluminium oxide, mica, titanium oxide-coated or iron oxide-coated
aluminium oxide, titanium oxide-coated or iron oxide-coated mica,
glass flakes, holographic pigments, etc. Such luster pigments (D3)
can be used singly or in a combination of two or more. Examples of
the aluminum pigment include leafing aluminum pigments and
non-leafing aluminum pigments. Any of the pigments can be used.
[0208] When the aqueous intermediate coating composition (X)
contains a luster pigment (D3) as described above, the amount of
luster pigment (D3) is typically 1 to 50 parts by mass, preferably
2 to 30 parts by mass, and even more preferably 3 to 20 parts by
mass, per 100 parts by mass of the total amount of base resin (A)
and curing agent (B) in the aqueous intermediate coating
composition (X), on a solids basis.
1.5.2 Hydrophobic Solvent (E)
[0209] From the viewpoint of improving the smoothness and
distinctness of image, the aqueous intermediate coating composition
(X) preferably further contains a hydrophobic solvent (E).
[0210] The hydrophobic solvent (E) is desirably an organic solvent
of which a mass of 10 g or less dissolves in 100 g of water at
20.degree. C., preferably 5 g or less, and more preferably 1 g or
less. Examples of the organic solvent include hydrocarbon solvents
such as rubber solvents, mineral spirits, toluene, xylene, and
solvent naphtha; alcoholic solvents such as 1-hexanol, 1-octanol,
2-octanol, 2-ethyl-1-hexanol, 1-decanol, benzyl alcohol, ethylene
glycol mono-2-ethylhexyl ether, propylene glycol mono-n-butyl
ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol
mono-n-butyl ether, propylene glycol mono-2-ethylhexyl ether, and
propylene glycol monophenyl ether; ester solvents such as n-butyl
acetate, isobutyl acetate, isoamyl acetate, methylamyl acetate, and
ethylene glycol monobutyl ether acetate; ketone solvents such as
methyl isobutyl ketone, cyclohexanone, ethyl n-amyl ketone, and
diisobutyl ketone; and the like. Such solvents can be used singly
or in a combination of two or more.
[0211] From the viewpoint of the smoothness of the resulting
coating film, it is preferable to use alcohol hydrophobic solvents
as the hydrophobic solvent (E). Among these, C.sub.7-14 hydrophobic
alcoholic solvents are preferable, and it is particularly
preferable to use at least one hydrophobic alcoholic solvent
selected from the group consisting of 1-octanol, 2-octanol,
2-ethyl-1-hexanol, ethylene glycol mono-2-ethylhexyl ether,
propylene glycol mono-n-butyl ether, and dipropylene glycol
mono-n-butyl ether.
[0212] When the aqueous intermediate coating composition (X)
contains a hydrophobic solvent (E) as mentioned above, the amount
of hydrophobic solvent (E) is preferably 2 to 50 parts by mass,
more preferably 5 to 40 parts by mass, and even more preferably 8
to 30 parts by mass, per 100 parts by mass of the total amount of
base resin (A), curing agent (B), and diester compound (C), on a
solids basis.
1.5.3 Curing Catalyst
[0213] The aqueous intermediate coating composition (X) may further
contain a curing catalyst. Examples of the curing catalyst include
organometallic compounds such as tin octylate, dibutyltin
di(2-ethylhexanoate), dioctyltin di(2-ethylhexanoate), dioctyltin
diacetate, dibutyltin dilaurate, dibutyltin oxide, dioctyltin
oxide, dibutyltin fatty acid salt, lead 2-ethylhexanoate, zinc
octylate, zinc naphthenate, zinc fatty acid salts, cobalt
naphthenate, calcium octylate, copper naphthenate, and
tetra(2-ethylhexyl)titanate; tertiary amine; phosphoric acid
compounds; and the like. Such compounds can be used singly or in a
combination of two or more.
[0214] When the aqueous intermediate coating composition (X)
contains a curing catalyst as mentioned above, the amount of curing
catalyst is usually 0.001 to 5 parts by mass, preferably 0.01 to
0.5 parts by mass, and more preferably 0.05 to 0.3 parts by mass,
per 100 parts by mass of the total amount of base resin (A) and
curing agent (B) in the aqueous intermediate coating composition
(X), on a solids basis.
1.5.4 Other Additives for Coating Composition
[0215] If necessary, the aqueous intermediate coating composition
(X) may contain additives for coating compositions, such as
thickening agents, UV absorbers, light stabilizers, antifoaming
agents, plasticizers, organic solvents other than the above
hydrophobic solvents (E), surface control agents, antisettling
agents, etc.
[0216] Examples of thickening agents include inorganic thickening
agents such as silicate, metal silicate, montmorillonite, colloidal
alumina, etc.; polyacrylic acid thickening agents such as
copolymers of (meth)acrylic acid and (meth)acrylic ester, sodium
polyacrylate, etc.; associative thickening agents having a
hydrophilic moiety and a hydrophobic moiety per molecule, and
which, in aqueous medium, effectively improve the viscosity by
adsorption of the hydrophobic moiety on the surface of pigments or
emulsion particles in a coating composition, or by association
between hydrophobic moieties; cellulose derivative thickening
agents such as carboxymethylcellulose, methylcellulose,
hydroxyethylcellulose, etc.; protein thickening agents such as
casein, sodium caseinate, ammonium caseinate, etc.; alginate
thickening agents such as sodium alginate, etc.; polyvinyl
thickening agents such as polyvinyl alcohol, polyvinylpyrrolidone,
polyvinyl benzyl ether copolymers, etc.; polyether thickening
agents such as pluronic polyether, polyether dialkyl ester,
polyether dialkyl ether, polyether epoxy-modified products, etc.;
maleic anhydride copolymer thickening agents such as partial esters
of a copolymer of vinyl methyl ether and maleic anhydride, etc.;
polyamide thickening agents such as polyamide amine salts, etc.;
and the like. Such thickening agents can be used singly or in a
combination of two or more.
[0217] Examples of usable polyacrylic acid thickening agents
include commercially available products, which are available, for
example, under the tradenames "PRIMAL ASE-60", "PRIMAL TT-615", and
"PRIMAL RM-5", manufactured by Rohm and Haas; "SN Thickener 613",
"SN Thickener 618", "SN Thickener 630", "SN Thickener 634", and "SN
Thickener 636", manufactured by San Nopco Ltd.; and the like.
Examples of usable associative thickening agents include
commercially available products, which are available, for example,
under the tradenames "UH-420", "UH-450", "UH-462", "UH-472",
"UH-540", "UH-752", "UH-756VF", and "UH-814N", manufactured by
ADEKA Co. Ltd.; "PRIMAL RM-8W", "PRIMAL RM-825", "PRIMAL
RM-2020NPR", "PRIMAL RM-12W", and "PRIMAL SCT-275", manufactured by
Rohm and Haas; "SN Thickener 612", "SN Thickener 621N", "SN
Thickener 625N", "SN Thickener 627N", and "SN Thickener 660T",
manufactured by San Nopco Ltd.; and the like.
[0218] As a thickening agent, it is preferable to use a polyacrylic
acid thickening agent and/or an associative thickening agent, more
preferably an associative thickening agent, and still more
preferably a urethane associative thickening agent bearing a
hydrophobic group at its end(s) and having a urethane bond in a
molecular chain. Examples of usable urethane associative thickening
agents include commercially available products, which are
available, for example, under the tradenames "UH-420", "UH-462",
"UH-472", "UH-540", "UH-752", "UH-756VF", and "UH-814N",
manufactured by ADEKA Co. Ltd.; "SN thickener 612", "SN thickener
621N", "SN thickener 625N", "SN thickener 627N", and "SN thickener
660T", manufactured by San Nopco Ltd.; and the like.
[0219] When the aqueous intermediate coating composition (X)
comprises a thickening agent as described above, the amount thereof
is preferably about 0.01 to about 10 parts by mass, more preferably
about 0.02 to about 3 parts by mass, and still more preferably
about 0.03 to about 2 parts by mass, per 100 parts by mass of the
total solids content of the base resin (A), curing agent (B) and
diester compound (C).
[0220] The aqueous intermediate coating composition (X) can be
prepared by mixing and dispersing, in an aqueous medium, a base
resin (A), a curing agent (B), and a diester compound (C), together
with, if necessary, a melamine resin (B3-1), a pigment (D), a
hydrophobic solvent (E), and other additives for coating
compositions, using a known method. Examples of usable aqueous
media include deionized water, and a mixture of deionized water and
hydrophilic organic solvent. Examples of hydrophilic organic
solvents include propylene glycol monomethyl ether etc.
[0221] It is usually preferable that the solids content of the
aqueous intermediate coating composition (X) be about 30 to about
80 mass %, more preferably about 40 to about 70 mass %, and still
more preferably about 45 to about 60 mass %.
[0222] The aqueous intermediate coating composition (X) according
to the present invention may be a single-component coating
composition, or a multi-component coating composition; however, the
following two-component coating compositions are preferable in view
of storage stability etc.
[0223] 1) A two-component coating composition consisting of a main
agent (X1) that contains a hydroxy-containing resin (A1) and a
diester compound (C), and a curing agent (X2) that contains a
polyisocyanate compound (B1). It is usually preferable that the
main agent (X1) further contain a pigment, a curing catalyst, and
water, and that the curing agent (X2) further contain a
solvent.
[0224] 2) It is preferable to form a two-component coating
composition consisting of a main agent (X1) that contains a
carboxy-containing resin (A2) and a diester compound (C), and a
curing agent (X2) that contains a polycarbodiimide compound (B2).
It is generally desirable that the main agent (X1) further contain
a pigment, a curing catalyst, and water, and that the curing agent
(X2) further contain water. The curing agent (X2) may further
contain a surfactant.
[0225] The curing agent (X2) may further contain a surfactant.
Preferable as the surfactant are anionic surfactants and/or
nonionic surfactants; anionic surfactants are more preferable. When
the curing agent (X2) contains a surfactant, the polyisocyanate
compound (B1) is dispersed in an aqueous intermediate coating
composition (X) in a relatively uniform manner while mixing the
main agent (X1) and the curing agent (X2). This allows the
intermediate coating layer to cure uniformly, thereby forming a
coating film with excellent smoothness and distinctness of
image.
[0226] From the viewpoint of the smoothness, distinctness of image,
flip-flop effect, decrease in metallic mottling, etc. of the
resulting coating film, it is preferable that the aqueous
intermediate coating composition (X) according to the present
invention be applied to a cured film thickness of 30 .mu.m, and
have a gel fraction (G.sub.80) of generally about 5 to about 100
mass %, preferably about 10 to about 95 mass %, more preferably
about 15 to about 95 mass %, and even more preferably about 30 to
about 90 mass %, after being heated at 80.degree. C. for 10
minutes.
[0227] The gel fraction (G.sub.80) can be calculated according to
the following method:
[0228] First, the aqueous intermediate coating composition (X) is
applied to a polypropylene plate to a cured film thickness of 30
.mu.m, and then heated at 80.degree. C. for 10 minutes. The
intermediate coating layer over the polypropylene plate is
collected to measure the mass (W.sub.a). The layer is then placed
into a stainless steel container with a 300-mesh sieve, extracted
for 5 hours in a solvent mixture containing an equivalent amount of
acetone and methanol that has been heated to 64.degree. C., and
then dried at 110.degree. C. for 60 minutes. The mass (W.sub.b) of
the resulting coating layer is then measured. The remaining ratio
(mass %) of the insoluble coating layer is calculated according to
the following formula and is referred to as a gel fraction
(G.sub.80).
Gel fraction (G.sub.80) mass %=(W.sub.b/W.sub.a).times.100
[0229] The gel fraction (G.sub.80) of the coating composition of
the present invention can be determined by adjusting the proportion
of the curing catalyst in the coating composition.
[0230] The aqueous intermediate coating composition (X) can be
applied on the substrate using known methods such as air spray
coating, airless spray coating, rotary atomization coating, curtain
coating, etc. An electrostatic charge may be applied during
coating. Among these, air spray coating and rotary atomization
coating are preferable.
[0231] It is preferable that the aqueous intermediate coating
composition (X) be applied in such a manner that the cured film
thickness becomes usually about 5 to about 70 .mu.m, preferably
about 10 to about 50 .mu.m, and more preferably about 15 to about
40 .mu.m.
2. Step (2)
[0232] Subsequently, the aqueous base coating composition (Y) is
applied to the layer of the aqueous intermediate coating
composition (X) (hereinafter sometimes referred to as "intermediate
coating film") formed in Step (1).
[0233] It is preferable to perform, prior to the application of the
aqueous base coating composition (Y), preheating, air blowing, etc.
on the intermediate coating film under conditions in which the
coating film does not substantially cure.
[0234] In the present invention, a cured coating film indicates a
film in a dry hard condition according to JIS K 5600-1-1, i.e., a
condition in which an imprint due to a fingerprint is not formed on
the coating surface and no movement is detected on the coated film
when the center of the surface is strongly pinched with a thumb and
an index finger, or in which a scrape is unobservable on the
coating surface when the center of the surface is rubbed repeatedly
with a fingertip; the uncured coating film indicates a film that
has not yet reached a dry hard condition, including a film in a set
to touch condition and a film in a dry to touch condition according
to JIS K 5600-1-1.
[0235] The preheating temperature is preferably about 40 to about
100.degree. C., more preferably about 50 to about 90.degree. C.,
and still more preferably about 60 to about 80.degree. C. The
preheating time is preferably about 30 seconds to about 15 minutes,
more preferably about 1 to about 10 minutes, and still more
preferably about 2 to about 5 minutes. Air blowing can usually be
performed by blowing room temperature air or air heated to about 25
to about 80.degree. C. over the coated surface of the substrate for
about 30 seconds to about 15 minutes.
[0236] It is preferable to adjust the solids content of the
intermediate coating film to generally about 60 to about 100 mass
%, preferably about 80 to about 100 mass %, and more preferably
about 90 to about 100 mass % by means of preheating, air blowing,
etc., prior to the application of the aqueous base coating
composition (Y).
[0237] It is further preferable to adjust the gel fraction of the
coating film to the range described below.
[0238] When the aqueous intermediate coating composition (X)
contains a hydroxy-containing resin (A1) and/or a hydroxy- and
carboxy-containing resin (A3), a polyisocyanate compound (B1), and
a diester compound (C), it is preferable to adjust the gel fraction
of the coating film to within the range of generally about 1 to
about 95 mass %, preferably about 15 to about 92 mass %, and more
preferably about 20 to 90 mass %.
[0239] When the aqueous intermediate coating composition (X)
contains a carboxy-containing resin (A2) and/or a hydroxy- and
carboxy-containing resin (A3), a polycarbodiimide compound (B2) and
a diester compound (C), it is preferable to adjust the gel fraction
of the coating film to within the range of generally about 1 to
about 95 mass %, preferably about 5 to 90 mass %, and more
preferably about 10 to about 85 mass %.
[0240] The solids content of the coating film is calculated
according to the following method:
[0241] First, an aqueous intermediate coating composition (X) is
applied to the substrate. The aqueous intermediate coating
composition (X) is also applied to an aluminum foil whose content
(W.sub.1) is previously measured. The aluminum foil is subjected to
preheating and like treatment after application, and then collected
just before the application of the aqueous base coating composition
(Y). The content thereof (W.sub.2) is measured. Subsequently, the
collected aluminum foil is dried at 110.degree. C. for 60 minutes
and allowed to cool to room temperature in a desiccator, thereby
obtaining the mass (W.sub.3) of the aluminum foil. The solids
content is then measured according to the following formula.
Solids content mass
%={(W.sub.3-W.sub.1)/(W.sub.2-W.sub.1)}.times.100
[0242] The gel fraction of the coating film can be calculated
according to the following method:
[0243] First, an aqueous intermediate coating composition (X) is
applied to a substrate. The aqueous intermediate coating
composition (X) is also applied to a polypropylene plate, and
preheated. The polypropylene plate that is subjected to preheating
and like treatment after application is collected just before the
application of the aqueous base coating composition (Y). The
intermediate coating film on the polypropylene plate is then
collected to measure its mass (W.sub.C). The film is placed into a
stainless steel container with a 300-mesh sieve, extracted for 5
hours in a solvent mixture containing an equivalent amount of
acetone and methanol that has been heated to 64.degree. C., and
then dried at 110.degree. C. for 60 minutes. The mass (W.sub.d) of
the resulting coating film is then measured. The remaining ratio
(mass %) of the insoluble coating film is calculated according to
the following formula, and is referred to as a gel fraction.
Gel fraction mass %=(W.sub.d/W.sub.c).times.100
[0244] The aqueous base coating composition (Y) applied on the
intermediate coating film is generally intended to impart an
excellent appearance to a substrate. For example, a coating
composition obtained by dissolving or dispersing, in water, a resin
component comprising a base resin and a curing agent, together with
pigments and other additives.
[0245] Examples of the base resin include acrylic resins, polyester
resins, alkyd resins, urethane resins, epoxy resins, etc., all
containing crosslinkable functional groups such as carboxy groups,
hydroxy groups, etc. Examples of the curing agent include blocked
or unblocked polyisocyanate compounds, melamine resins, urea
resins, etc. Among these, a thermosetting aqueous coating
composition containing the hydroxy-containing resin (A1) as a base
resin and the melamine resin (B3-1) as a curing agent, and a
thermosetting aqueous coating composition containing the carboxy-
and hydroxy-containing resin (A3) as a base resin and the melamine
resin (B3-1) as a curing agent can be advantageously used in view
of the appearance, water-resistance, etc. of the resulting
multilayer coating film.
[0246] The coloring pigment (D1), extender pigment (D2), luster
pigment (D3), etc., can be used as the above-mentioned pigment. It
is particularly preferable that the aqueous base coating
composition (Y) contain the coloring pigment and/or luster pigment
(D3) as at least one of the pigments described above.
[0247] Examples of the coloring pigment (D1) include titanium
oxide, zinc flower, carbon black, molybdenum red, Prussian blue,
cobalt blue, azo pigments, phthalocyanine pigments, quinacridone
pigments, isoindoline pigments, threne pigments, perylene pigments,
dioxazine pigments, diketo-pyrrolo-pyrrole pigments, etc. as
mentioned in the description of the aqueous intermediate coating
composition (X).
[0248] When the aqueous base coating composition (Y) includes the
coloring pigment (D1), the amount of the coloring pigment (D1) is
preferably about 1 to about 150 parts by mass, more preferably
about 3 to about 130 parts by mass, and even more preferably about
5 to about 110 parts by mass, per 100 parts by mass of the resin
solids content in the aqueous base coating composition (Y).
[0249] Examples of the luster pigment (D3) include aluminum
(including vapor-deposited aluminum), copper, zinc, brass, nickel,
aluminum oxide, mica, titanium oxide-coated or iron oxide-coated
aluminum oxide, titanium oxide-coated or iron oxide-coated mica,
glassflakes, hologram pigment, etc., as mentioned in the
description of the aqueous intermediate coating composition (X).
Among these, aluminum, aluminum oxide, mica, titanium oxide- or
iron oxide-coated aluminum oxide, and titanium oxide-coated or iron
oxide-coated mica are more preferable, and aluminum is even more
preferable. Such luster pigments (D3) can be used singly or in a
combination of two or more.
[0250] The luster pigment (D3) is preferably in the form of flakes.
More specifically, the preferable luster pigment (D3) has a
longitudinal dimension of about 1 to about 100 .mu.m, and
preferably about 5 to about 40 .mu.m, and a thickness of about
0.001 to about 5 .mu.m, and preferably about 0.01 to about 2
.mu.m.
[0251] When the aqueous base coating composition (Y) includes the
luster pigment (D3), the amount of the luster pigment (D3) is
preferably about 1 to about 50 parts by mass, more preferably about
2 to about 30 parts by mass, and even more preferably about 3 to
about 20 parts by mass, per 100 parts by mass of the resin solids
in the aqueous base coating composition (Y).
[0252] When the aqueous base coating composition (Y) contains the
luster pigment (D3) in the method for producing a multilayer
coating film of the present invention, it is possible to form a
multilayer coating film having excellent appearance with excellent
smoothness and distinctness of image, a high flip-flop effect, and
little metallic mottling.
[0253] This is presumably because, by using the aqueous
intermediate coating composition (X) containing the diester
compound (C), an intermediate coating film with appropriate
hydrophilicity is formed, and the aqueous base coating composition
(Y) applied on the intermediate coating film uniformly wets and
spreads over the intermediate coating film, so that the luster
pigment (D3) in the aqueous base coating composition (Y) is present
in the base coating film in a relatively uniform state and is
likely to be oriented parallel to the substrate, thereby forming a
coating film having excellent appearance with a high flip-flop
effect and little metallic mottling.
[0254] It is preferable that the aqueous base coating composition
(Y) contain the hydrophobic solvent (E). From the viewpoint of the
brilliance of the resulting coating film, it is preferable to use
an alcohol hydrophobic solvent as the hydrophobic solvent (E). In
particular, C.sub.7-14 alcohol hydrophobic solvents are preferable.
For example, it is particularly preferable to use at least one
alcohol hydrophobic solvent selected from the group consisting of
1-octanol, 2-octanol, 2-ethyl-1-hexanol, ethylene glycol
mono-2-ethylhexyl ether, propylene glycol mono-n-butyl ether, and
dipropylene glycol mono-n-butyl ether.
[0255] When the aqueous base coating composition (Y) contains the
hydrophobic solvent (E), the amount thereof is preferably about 2
to about 70 parts by mass, more preferably about 11 to about 60
parts by mass, and even more preferably about 16 to about 50 parts
by mass, per 100 parts by mass of the resin solids content in the
aqueous base coating composition (Y).
[0256] The aqueous base coating composition (Y) may further
contain, if necessary, conventional additives for coating
compositions, such as curing catalysts, thickening agents, UV
absorbers, light stabilizers, antifoaming agents, plasticizers,
organic solvents, surface control agents, antisettling agents, etc.
Such additives can be used singly or in a combination of two or
more.
[0257] The aqueous base coating composition (Y) can be applied
using known methods such as air spray coating, airless spray
coating, rotary atomization coating, etc. An electrostatic charge
may be applied during coating. The coating is formed so as to
obtain a cured film with a thickness of usually about 5 to about 30
.mu.m, preferably about 8 to about 25 .mu.m, and more preferably
about 10 to about 20 .mu.m.
3. Step (3)
[0258] In the method for forming a multilayer coating film of the
present invention, the clear coating composition (Z) is applied to
the layer of the aqueous base coating composition (Y) (hereinafter
sometimes referred to as "base coating film") formed in the above
step (2).
[0259] It is preferable to perform, prior to the application of the
clear coating composition (Z), preheating, air blowing, etc. on a
clear coating layer under conditions in which the coating layer
does not substantially cure. The preheating temperature is
preferably about 40 to about 100.degree. C., more preferably about
50 to about 90.degree. C., and still more preferably about 60 to
about 80.degree. C. The preheating time is preferably about 30
seconds to about 15 minutes, more preferably about 1 to about 10
minutes, and still more preferably about 2 to about 5 minutes. Air
blowing can usually be performed by blowing room temperature air or
air heated to about 25 to about 80.degree. C. over the coated
surface of the substrate for about 30 seconds to 15 minutes.
[0260] It is preferable to adjust the solids content of the base
coating film to generally about 70 to about 100 mass %, preferably
about 80 to about 100 mass %, and more preferably about 90 to about
100 mass % by means of preheating, air blowing, etc., prior to the
application of the clear coating composition (Z).
[0261] As the clear coating composition (Z), any known
thermosetting clear coating compositions for coating an automobile
body and the like can be used. Examples thereof include
organic-solvent thermosetting coating compositions, aqueous
thermosetting coating compositions, and powder thermosetting
coating compositions, which comprise a crosslinking agent and a
base resin having a crosslinkable functional group.
[0262] Examples of crosslinkable functional groups contained in a
base resin include carboxy, hydroxy, epoxy, silanol, and the like.
Examples of the kinds of base resins include acrylic resins,
polyester resins, alkyd resins, urethane resins, epoxy resins,
fluororesins, and the like. Examples of crosslinking agents include
polyisocyanate compounds, blocked polyisocyanate compounds,
melamine resins, urea resins, carboxy-containing compounds,
carboxy-containing resins, epoxy-containing resins,
epoxy-containing compounds, and the like.
[0263] Examples of preferable combinations of base
resin/crosslinking agent for the clear coating composition (Z) are
carboxy-containing resin/epoxy-containing resin, hydroxy-containing
resin/polyisocyanate compound, hydroxy-containing resin/blocked
polyisocyanate compound, hydroxy-containing resin/melamine resin,
and the like.
[0264] The clear coating composition (Z) may be a one-component
coating composition, or a multi-component coating composition such
as a two-component urethane resin coating composition.
[0265] If necessary, the clear coating composition (Z) may contain
a coloring pigment (D1), luster pigment (D3), dye, etc., in a
degree such that the transparency of the clear coating composition
is not impaired, and may also contain an extender pigment (D2), UV
absorber, light stabilizer, antifoaming agent, thickening agent,
anticorrosive, surface control agent, etc.
[0266] The clear coating composition (Z) can be applied on the
surface of the aqueous base coating composition (Y) using known
methods such as airless spray coating, air spray coating, rotary
atomization coating, etc. An electrostatic charge may be applied
during coating.
[0267] The clear coating composition (Z) is applied to a cured film
thickness of generally about 10 to about 80 .mu.m, preferably about
15 to about 60 .mu.m, and more preferably about 20 to about 50
.mu.m.
[0268] After application of the clear coating composition (Z), if
necessary, it is possible to have an interval of about 1 to about
60 minutes at room temperature, or perform preheating at about 40
to about 80.degree. C. for about 1 to about 60 minutes.
4. Step (4)
[0269] In the method of forming a multilayer coating film of the
present invention, the uncured intermediate coating layer, uncured
base coating layer, and uncured clear coating layer formed in Steps
(1) to (3) are simultaneously heat-cured.
[0270] The intermediate coating layer, base coating layer, and
clear coating layer are cured by a usual baking method, such as
air-blowing, infrared heating, high frequency heating, and the
like.
[0271] The heating temperature is preferably about 80 to about
180.degree. C., more preferably about 100 to about 170.degree. C.,
and still more preferably about 120 to about 160.degree. C.
[0272] The heating time is preferably about 10 to about 60 minutes,
and more preferably about 15 to about 40 minutes. This heating
allows the multilayer coating film consisting of three layers,
i.e., an intermediate coating layer, base coating layer and clear
coating layer to be simultaneously cured.
EXAMPLES
[0273] The present invention is described below in more detail with
reference to Examples and Comparative Examples. However, the
present invention is not limited to these examples. In the
examples, "parts" and "%" are expressed on a weight basis.
Production of Hydroxy- and Carboxy-Containing Resin (A3)
Production of Hydroxy- and Carboxy-Containing Polyester Resin
(A3-1)
Production Example 1-1
[0274] Eighty eight grams of adipic acid, 490 g of
1,2-cyclohexanedicarboxylic acid anhydride, 199 g of isophthalic
acid, 336 g of 2-butyl-2-ethyl-1,3-propanediol, 189 g of
neopentylglycol, and 287 g of trimethylolpropane were placed into a
reaction vessel equipped with a thermometer, a thermostat, a
stirrer, a reflux condenser and a water separator, and heated from
160.degree. C. to 230.degree. C. over 3 hours. The reaction was
maintained at 230.degree. C. while removing the condensation water
using a water separator, and was allowed to proceed until the acid
value became 5 mg KOH/g or less. 48 g of trimellitic anhydride was
added to the reaction product, and an addition reaction was
performed at 170.degree. C. for 30 minutes. Subsequently, the
resultant was cooled to 50.degree. C. or less, and neutralized by
adding 0.9 equivalents of 2-(dimethylamino)ethanol relative to acid
groups. Then, deionized water was gradually added to obtain an
aqueous hydroxy- and carboxy-containing polyester resin dispersion
(A3-1-1) with a solids content of 45% and a pH of 7.2. The
resulting hydroxy- and carboxy-containing polyester resin had an
acid value of 24 mg KOH/g, a hydroxy value of 150 mg KOH/g, and a
number average molecular weight of 1,310.
[0275] The content of the C.sub.4 or higher linear alkylene group
in the resulting hydroxy- and carboxy-containing polyester resin is
calculated using the following formula.
The molar number of the C 4 or higher linear alkylene group ( Wm )
= 88 / 146 ( adipic acid ) = 0.603 mol ##EQU00001## The mass of
condensation water = 18 .times. { 2 .times. 199 / 166 ( isophthalic
acid ) + 1 .times. 490 / 154 ( 1 , 2 - cyclohexanedicarboxylic
anhydride ) + 2 .times. 88 / 146 ( adipic acid ) } = 122 g
##EQU00001.2## The resulting amount of the resin without the
condensation water ( Wr ) = 287 ( trimethylolpropane ) + 336 ( 2 -
butyl - 2 - ethyl - 1 , 3 - propanediole ) + 189 ( neopentyl glycol
) + 199 ( isophthalic acid ) + 490 ( 1 , 2 -
cyclohexanedicarboxylic anhydride ) + 88 ( adipic acid ) + 48 (
trimellitic anhydride ) - 122 ( condensation water ) = 1515 g =
1.515 kg ##EQU00001.3## The content of the C 4 or higher linear
alkylene group = The number of mol of the C 4 or higher linear
alkylene group ( Wm ) / the resulting amount of the resin without
condensation water ( Wr ) = 0.603 / 1.515 = 0.4 mol / kg ( resin
solids content ) ##EQU00001.4##
[0276] The total amount of the benzene ring and the cyclohexane
ring in the resulting hydroxy- and carboxy-containing polyester
resin was calculated according to the following formula.
The total molar number of the benzene ring and the cyclohexane ring
( Wn ) = 199 / 166 ( isophtalic acid ) + 490 / 154 ( 1 , 2 -
cyclophexanedicarboxylic anhydride ) + 48 / 192 ( trimellitic
anhydride ) = 4.63 mol ##EQU00002## The total amount of the benzene
ring and the cyclohexane ring = The total molar number of the
benzene ring and the cyclohexane ring ( Wn ) / the resulting amount
of the resin without the condensation water ( Wr ) = 4.63 / 1.515 =
3.1 mol / kg ( resin solids content ) ##EQU00002.2##
Production Examples 1-2 to 1-12
[0277] According to the proportions shown in Tables 1 and 2 below,
aqueous hydroxy- and carboxy-containing polyester resin dispersions
(A3-1-2) to (A3-1-12), each having a solids content of 45% and a pH
of 7.2 were obtained in the same manner as in Example 1-1. Tables 1
and 2 show the content of the C.sub.4 or higher linear alkylene
group, total amount of the benzene ring and the cyclohexane ring,
acid value, hydroxy value, and number average molecular weight of
each of the resulting hydroxy- and carboxy-containing polyester
resins, along with those of the aqueous hydroxy- and
carboxy-containing polyester resin dispersion (A3-1-1) obtained in
Production Example 1-1.
TABLE-US-00001 TABLE 1 Production Example 1-1 1-2 1-3 1-4 1-5 1-6
Hydroxy- and carboxy-containing polyester resin A3-1-1 A3-1-2
A3-1-3 A3-1-4 A3-1-5 A3-1-6 Acid Aliphatic polybasic Adipic acid
(Mw 146) 88 88 420 263 263 263 component acid (a1-1-1)
Dodecanedioic acid (Mw 230) (a1-1) Alicyclic polybasic
1,2-Cyclohexanedicarboxylic 490 490 231 305 305 305 acid (a1-1-2)
anhydride (Mw 154) Aromatic polybasic Isophthalic acid (Mw 166) 199
199 100 199 199 199 acid (a1-1-3) Alcohol Aliphatic diol
1,6-Hexanediol (Mw 118) 212 component (a1-2-1) 1,9-Nonanediol (Mw
160) 288 (a1-2) 2-Butyl-2-ethyl-1,3-propane 336 288 355 336 240 240
diol (Mw 160) Neopentyl glycol (Mw 105) 189 95 189 50 Alicyclic
diol 1,4-Cyclohexane dimethanol 173 173 86 86 (a1-2-2) (Mw 144)
Trimethylolpropane (Mw 134) 287 287 270 303 287 287 Acid Aromatic
polybasic Trimellitic anhydride (Mw 192) 48 48 48 48 48 51
component acid (a1-1-3) (a1-1) Content of C.sub.4 or higher linear
alkylene 0.4 0.4 2.0 1.2 2.4 2.3 [mmol/g(resin solids content)]
Total amount of benzene ring and cyclohexane ring 3.1 3.8 1.6 3.0
2.7 2.6 [mmol/g(resin solids content)] Acid value [mg KOH/g] 24 23
25 23 24 24 Hydroxy value [mg KOH/g] 150 146 150 152 151 148 Number
average molecular weight 1310 1330 1270 1330 1300 1350 Weight
average molecular weight 10800 10900 10400 11200 10700 11500
TABLE-US-00002 TABLE 2 Production Example 1-7 1-8 1-9 1-10 1-11
1-12 Hydroxy- and carboxy-containing polyester resin A3-1-7 A3-1-8
A3-1-9 A3-1-10 A3-1-11 A3-1-12 Acid Aliphatic polybasic Adipic acid
(Mw 146) 44 438 464 88 component acid (a1-1-1) Dodecanedioic acid
(Mw 230) 138 276 (a1-1) Alicyclic polybasic
1,2-Cyclohexanedicarboxylic 490 490 370 305 277 397 acid (a1-1-2)
anhydride (Mw 154) Aromatic polybasic Isophthalic acid (Mw 165) 199
100 378 299 acid (a1-1-3) Alcohol Aliphatic diol 1,6-Hexanediol (Mw
118) 142 component (a1-2-1) 1,9-Nonanediol (Mw 160) (a1-2)
2-Butyl-2-ethyl-1,3-propane 336 336 336 154 336 288 diol (Mw 160)
Neopentyl glycol (Mw 105) 176 164 183 202 Alicyclic diol
1,4-Cyclohexane dimethanol 259 285 (a1-2-2) (Mw 144)
Trimethylolpropane (Mw 134) 303 319 295 278 270 303 Acid Aromatic
polybasic Trimellitic anhydride (Mw 192) 48 53 53 53 50 50
component acid (a1-1-3) (a1-1) Content of C.sub.4 or higher linear
alkylene 0.4 0.7 0.2 2.8 2.2 0.4 [mmol/g(resin solids content)]
Total amount of benzene ring and cyclohexane ring 3.0 2.5 3.3 2.7
1.4 4.2 [mmol/g(resin solids content)] Acid value [mg KOH/g] 23 24
24 25 24 23 Hydroxy value [mg KOH/g] 148 147 150 149 148 148 Number
average molecular weight 1353 1394 1310 1290 1320 1360 Weight
average molecular weight 10900 12200 10500 10400 10700 10900
Production of Hydroxy- and Carboxy-Containing Acrylic Resin
(A3-2)
Production Example 1-13
[0278] A 30 part quantity of propylene glycol monopropyl ether was
placed into a reaction vessel equipped with a thermometer, a
thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube
and a dropping funnel, and heated to 85.degree. C. A mixture of 10
parts of styrene, 30 parts of methyl methacrylate, 15 parts of
2-ethylhexyl acrylate, 11.5 parts of n-butyl acrylate, 30 parts of
hydroxyethyl acrylate, 3.5 parts of acrylic acid, 10 parts of
propylene glycol monopropyl ether and 2 parts of
2,2'-azobis(2,4-dimethylvaleronitrile) was added dropwise over 4
hours, and then aged for 1 hour. A mixture of 5 parts of propylene
glycol monopropyl ether and 1 part of
2,2'-azobis(2,4-dimethylvaleronitrile) was further added dropwise
into a flask for 1 hour, and after completion of the dropwise
addition, aging was conducted for 1 hour. Subsequently, 3.03 parts
of 2-(dimethylamino)ethanol was added. Deionized water was
gradually added to thereby obtain a hydroxy- and carboxy-containing
acrylic resin dispersion (A3-2-1) with a solids content of 40%. The
resulting hydroxy- and carboxy-containing acrylic resin had an acid
value of 27 mg KOH/g, a hydroxy value of 145 mg KOH/g, and a weight
average molecular weight of 24,000.
Production Example 1-14
[0279] A 70.7 part quantity of deionized water and 0.52 parts of
polyoxyethylene alkyl ether sulfate ester ammonium salt (trade name
"Aqualon KH-10" produced by Dai-Ichi Kogyo Seiyaku Co., Ltd.,
active ingredient: 97%) were placed into a reaction vessel equipped
with a thermometer, a thermostat, a stirrer, a reflux condenser, a
nitrogen inlet tube and a dropping funnel. The mixture was stirred
and mixed in a nitrogen flow, and heated to 80.degree. C.
Subsequently, 1% of the total amount of the emulsified monomer (1)
described below and 5 parts of 6% ammonium persulfate solution were
introduced into a reaction vessel, and maintained at 80.degree. C.
for 15 minutes. The remaining emulsified monomer (1) was added
dropwise into a reaction vessel over 3 hours while the same
temperature was maintained. After completion of the dropwise
addition, the reaction product was aged for 1 hour. Gradually
adding 40 parts of 5% 2-(dimethylamino)ethanol solution into a
reaction vessel, the reaction product was cooled to 30.degree. C.,
and filtrated using 100-mesh nylon cloth to obtain a filtrate of an
aqueous hydroxy- and carboxy-containing acrylic resin dispersion
(A3-2-2) with a solids content of 45%. The resulting hydroxy- and
carboxy-containing acrylic resin had an acid value of 12 mg KOH/g,
a hydroxy value of 43 mg KOH/g, and a weight average molecular
weight of 150,000.
[0280] Emulsified monomer (1): Emulsified monomer (1) was obtained
by mixing and stirring 50 parts of deionized water, 10 parts of
styrene, 40 parts of methyl methacrylate, 35 parts of
ethylacrylate, 3.5 parts of n-butyl methacrylate, 10 parts of
2-hydroxyethyl methacrylate, 1.5 parts of acrylic acid, 1.0 part of
Aqualon KH-10 and 0.03 parts of ammonium persulfate.
Production of Water-Dispersible Polyisocyanate Compound (B1)
Production Example 1-15
[0281] A 165 part quantity of tolonate HDT (NCO %=21.9%, a
polyisocyanate compound produced by Rhodia Co., Ltd.), 24 parts of
butyl acetate, 13 parts of Rhodafac RE610 (a surfactant produced by
Rhodia Co., Ltd.) and 3 parts of triethylamine were mixed under
stirring using a disperser at 100 rpm for 5 minutes. The
water-dispersible polyisocyanate compound (B1-3) was thus
obtained.
Production of Aqueous Intermediate Coating Composition (X1)
Production Example 1-16
[0282] A 44 part quantity (resin solids content: 20 parts) of
aqueous hydroxy- and carboxy-containing polyester resin dispersion
(A3-1-1) obtained in Production Example 1-1, 60 parts of rutile
titanium dioxide (D1-1) (trade name "JR-806", produced by TAYCA
CORP.), 1 part of carbon black (D1-2) (trade name "Carbon MA-100",
produced by Mitsubishi Chemical, Inc.), 15 parts of barium sulfate
powder (D2-1) (trade name "Bariace B-35", produced by Sakai
Chemical Industry Co., Ltd.) having an average primary particle
diameter of 0.5 .mu.m, 3 parts of powdered talc (D2-2) (trade name
"MICRO ACE S-3", produced by Nippon Talc Co., Ltd) having an
average primary particle diameter of 4.8 .mu.m, and 11 parts of
deionized water were mixed. After being adjusted to a pH of 8.0
with 2-(dimethylamino)ethanol, the mixture was dispersed using a
paint shaker for 30 minutes to obtain a pigment dispersion
paste.
[0283] Next, 134 parts of the resulting pigment dispersion paste,
98 parts of the aqueous hydroxy- and carboxy-containing polyester
resin dispersion (A3-1-1) obtained in Production Example 1-1, 10
parts of a diester compound (C-1) described below, and 10 parts of
a hydrophobic solvent (E-1) (2-ethyl-1-hexanol (mass dissolved in
100 g of water at 20.degree. C.: 0.1 g)) were homogeneously mixed
to obtain a main agent.
[0284] Diester compound (C-1): a diester compound of
polyoxyethylene glycol and n-hexanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
pentyl, R.sup.3 is ethylene, and m is 5. This diester compound has
a molecular weight of 434.
[0285] Subsequently, 26 parts of polyisocyanate compound (B1-1)
(trade name "Bayhydrol XP2570" produced by Sumika Bayer Urethane
Co., Ltd., an anionic hydrophilic water-dispersible polyisocyanate
compound, solids content: 100%, NCO content: 20.6%), a urethane
associative thickening agent (trade name "UH-752", produced by
ADEKA Co., Ltd.), 2-(dimethylamino)ethanol, and deionized water
were added to the resulting main agent, to obtain an aqueous
intermediate coating composition (X1-1) having a pH of 8.0, a
solids content of 48%, and a viscosity of 40 seconds as measured at
20.degree. C. using Ford Cup No. 4. The application was conducted
in such a manner that the resulting aqueous intermediate coating
composition (X1-1) had a cured film thickness of 30 .mu.m, and the
gel fraction (G.sub.80) of the coating film after being heated at
80.degree. C. for 10 minutes was 40%.
Production Examples 1-17 to 1-53, and 1-56 to 1-60
[0286] According to the proportions shown in Tables 3 to 9 below,
aqueous intermediate coating compositions (X1-2) to (X1-38) and
(X1-41) to (X1-45), each having a pH of 8.0, solids content of 48%,
and a viscosity of 40 seconds as measured at 20.degree. C. using
Ford Cup No. 4 were obtained in the same manner as in Example
1-16.
[0287] In Production Example 1-49, 25 parts of a
carbodiimide-containing compound (trade name "Carbodilite V-02"
produced by Nisshinbo Industries, Inc., solids content: 40%) was
further added during the production of the aqueous intermediate
coating composition (X). In production Example 1-50, 11 parts of
melamine resin (trade name "Cymel 327" produced by Japan Cytec
Industries, Inc., solids content: 90%) was further added during the
production of the aqueous intermediate coating composition (X). In
Production Example 1-53, 10 parts of ethylene glycol mono-n-butyl
ether (mass dissolved in 100 g of water at 20.degree. C.:
unlimited) was added in place of the hydrophobic solvent (E-1). In
Production Example 1-59, 29 parts of melamine resin (trade name
"Cymel 327" produced by Japanese Cytec Industries, Inc., solids
content 90%) was further added during the production of the aqueous
intermediate coating composition (X1). In Production Example 1-60,
68 parts of a blocked polyisocyanate compound (trade name
"Bayhydrol VP LS-2310" produced by Sumika Bayer Urethane Co., Ltd.,
solids content: 38%) was further added during the production of the
aqueous intermediate coating composition (X1).
[0288] The polyisocyanate compounds (B1-2) to (B1-4) represented in
Tables 3 to 9 below are as follows.
[0289] Polyisocyanate compound (B1-2): Bayhydrol VP LS-2319
produced by Sumika Bayer Urethane Co., Ltd., nonionic hydrophilic
water-dispersible polyisocyanate compound, solids content: 100%,
NCO content: 18.0%)
[0290] Polyisocyanate compound (B1-3): The water-dispersible
polyisocyanate compound obtained in Production Example 1-15
[0291] Polyisocyanate compound (B1-4): Desmodur XP 2410 (Sumika
Bayer Urethane Co., Ltd., solids content: 100%, NCO content:
24.0%)
[0292] Diester compounds (C-2) to (C-20) represented in Tables 3 to
9 below are as follows.
[0293] Diester compound (C-2): a diester compound of
polyoxyethylene glycol and 2-ethylbutanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are sec-butyl, R.sup.3 is ethylene, and m is 7. This
diester compound has a molecular weight of 522.
[0294] Diester compound (C-3): a diester compound of
polyoxyethylene glycol and 2-ethylpentanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethylbutyl, R.sup.3 is ethylene, and m is 7. This
diester compound has a molecular weight of 536.
[0295] Diester compound (C-4): a diester compound of
polyoxyethylene glycol and benzoic acid, the diester compound being
represented by Formula (1), wherein R.sup.1 and R.sup.2 are benzene
rings, R.sup.2 is ethylene, and m is 7. This diester compound has a
molecular weight of 536.
[0296] Diester compound (C-5): a diester compound of
polyoxyethylene glycol and n-octanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
heptyl, R.sup.3 is ethylene, and m is 7. This diester compound has
a molecular weight of 578.
[0297] Diester compound (C-6): a diester compound of
polyoxypropylene glycol and n-octanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
heptyl, R.sup.3 is propylene, and m is 7. This diester compound has
a molecular weight of 676.
[0298] Diester compound (C-7): a diester compound of
polyoxybutylene glycol and n-octanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
heptyl, R.sup.3 is butylene, and m is 7. This diester compound has
a molecular weight of 774.
[0299] Diester compound (C-8): a diester compound of
polyoxyethylene glycol and 2-ethylhexanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethylpentyl, R.sup.3 is ethylene, and m is 7. This
diester compound has a molecular weight of 578.
[0300] Diester compound (C-9): a diester compound of
polyoxyethylene glycol and n-nonoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
octyl, R.sup.3 is ethylene, and m is 7. This diester compound has a
molecular weight of 606.
[0301] Diester compound (C-10): a diester compound of
polyoxyethylene glycol and 2-ethylheptanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethyl hexyl, R.sup.3 is ethylene, and m is 7. This
diester compound has a molecular weight of 606.
[0302] Diester compound (C-11): a diester compound of
polyoxyethylene glycol and n-decanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
nonyl, R.sup.3 is ethylene, and m is 7. This diester compound has a
molecular weight of 634.
[0303] Diester compound (C-12): a diester compound of
polyoxyethylene glycol and 2-ethyloctanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethylheptyl, R.sup.3 is ethylene, and m is 10. This
diester compound has a molecular weight of 766.
[0304] Diester compound (C-13): a diester compound of
polyoxyethylene glycol and n-dodecanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
undecyl, R.sup.3 is ethylene, and m is 7. This diester compound has
a molecular weight of 690.
[0305] Diester compound (C-14): a diester compound of
polyoxyethylene glycol and n-octadecanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are heptadecyl, R.sup.3 is ethylene, and m is 7. This
diester compound has a molecular weight of 858.
[0306] Diester compound (C-15): a diester compound of
polyoxyethylene glycol and 2-ethylhexanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethylpentyl, R.sup.3 is ethylene, and m is 3. This
diester compound has a molecular weight of 402.
[0307] Diester compound (C-16): a diester compound of
polyoxyethylene glycol and 2-ethylhexanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethylpentyl, R.sup.3 is ethylene, and m is 5. This
diester compound has a molecular weight of 490.
[0308] Diester compound (C-17): a diester compound of
polyoxyethylene glycol and 2-ethylhexanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethylpentyl, R.sup.3 is ethylene, and m is 10. This
diester compound has a molecular weight of 710.
[0309] Diester compound (C-18): a diester compound of
polyoxyethylene glycol and 2-ethylhexanoic acid, the diester
compound being represented by Formula (1), wherein R.sup.1 and
R.sup.2 are 2-ethylpentyl, R.sup.3 is ethylene, and m is 25. This
diester compound has a molecular weight of 1370.
[0310] Diester compound (C-19): a diester compound of
polyoxyethylene glycol and n-butanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
n-propyl, R.sup.3 is ethylene, and m is 7. This diester compound
has a molecular weight of 466.
[0311] Diester compound (C-20): a diester compound of
polyoxyethylene glycol and n-icosanoic acid, the diester compound
being represented by Formula (1), wherein R.sup.1 and R.sup.2 are
nonadecyl, R.sup.3 is ethylene, and m is 7. This diester compound
has a molecular weight of 914.
Examples 1-54
[0312] A 44 part quantity (resin solids content: 20 parts) of the
aqueous hydroxy- and carboxy-containing polyester resin dispersion
(A3-1-1) obtained in Production Example 1-1, 60 parts of rutile
titanium dioxide (D1-1), 1 part of carbon black (D1-2), 15 parts of
barium sulfate powder (D2-1) having an average primary particle
diameter of 0.5 .mu.m, 3 parts of powdered talc (D2-2) having an
average primary particle diameter of 4.8 .mu.m and 11 parts of
deionized water were mixed. After being adjusted to a pH of 8.0
with 2-(dimethylamino)ethanol, the mixture was dispersed using a
paint shaker for 30 minutes to obtain a pigment dispersion
paste.
[0313] Next, 134 parts of the resulting pigment dispersion paste,
98 parts of the aqueous hydroxy- and carboxy-containing polyester
resin dispersion (A3-1-1) obtained in Production Example 1-1, 10
parts of the diester compound (C-8), and 10 parts of the
hydrophobic solvent (E-1) were homogenously mixed to obtain a main
agent.
[0314] Subsequently, 26 parts of the polyisocyanate compound
(B1-1), a polyacrylic acid thickening agent (trade name "Primal
ASE-60", produced by Rohm and Haas Company),
2-(dimethylamino)ethanol and deionized water were added to the main
agent to obtain an aqueous intermediate coating composition (X1-39)
having a pH of 8.0, a solids content of 48%, and a viscosity of 40
seconds measured at 20.degree. C. using Ford Cup No. 4.
Production Example 1-55
[0315] A 44 part quantity (resin solids content: 20 parts) of the
aqueous hydroxy- and carboxy-containing polyester resin dispersion
(A3-1-1) obtained in Production Example 1-1, 60 parts of rutile
titanium dioxide (D1-1), 1 part of carbon black (D1-2), 15 parts of
barium sulfate powder (D2-1) having an average primary particle
diameter of 0.5 .mu.m, 3 parts of powdered talc (D2-2) having an
average primary particle diameter of 4.8 .mu.m and 11 parts of
deionized water were mixed. After being adjusted to a pH of 8.0
with 2-(dimethylamino)ethanol, the mixture was dispersed using a
paint shaker for 30 minutes to obtain a pigment dispersion
paste.
[0316] Next, 134 parts of the resulting pigment dispersion paste,
98 parts of the aqueous hydroxy- and carboxy-containing polyester
resin dispersion (A3-1-1) obtained in Production Example 1-1, 10
parts of the above diester compound (C-8), and 10 parts of the
hydrophobic solvent (E-1) were homogenously mixed to obtain a main
agent.
[0317] Subsequently, 26 parts of the polyisocyanate compound
(B1-1), 2-(dimethylamino)ethanol and deionized water were added to
the main agent to obtain an aqueous intermediate coating
composition (X1-40) having a pH of 8.0, and a viscosity of 40
seconds as measured at 20.degree. C. using Ford Cup No. 4.
TABLE-US-00003 TABLE 3 Production Example 1-16 1-17 1-18 1-19 1-20
1-21 1-22 1-23 Aqueous intermediate coating composition (X1) X1-1
X1-2 X1-3 X1-4 X1-5 X1-6 X1-7 X1-8 Main Pigment Hydroxy- and Kind
A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 agent
dispersion carboxy-containing Content 44 44 44 44 44 44 44 44 paste
polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1
D1-1 D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 60 60 60 Kind D1-2
D1-2 D1-2 D1-2 D1-2 D1-2 D1-2 D1-2 Content 1 1 1 1 1 1 1 1 Extender
pigment Kind D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 (D2) Content
15 15 15 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 D2-2
D2-2 Content 3 3 3 3 3 3 3 3 Hydroxy- and carboxy-containing Kind
A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 polyester
resin (A3-1) Content 98 98 98 98 98 98 98 98 Diester compound (C)
Kind C-1 C-2 C-3 C-4 C-5 C-6 C-7 C-8 Content 10 10 10 10 10 10 10
10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1 E-1 E-1 E-1 E-1
Content 10 10 10 10 10 10 10 10 Curing Polyisocyanate compound (B1)
Kind B1-1 B1-1 B1-1 B1-1 B1-1 B1-1 B1-1 B1-1 agent Content 26 26 26
26 26 26 26 26 Gel fraction (G.sub.80) of the coating film after
being 40 39 38 43 41 41 41 38 heated at 80.degree. C. for 10
minutes [%]
TABLE-US-00004 TABLE 4 Production Example 1-24 1-25 1-26 1-27 1-28
1-29 1-30 1-31 Aqueous intermediate coating composition (X1) X1-9
X1-10 X1-11 X1-12 X1 -13 X1-14 X1-15 X1-16 Main Pigment Hydroxy-
and Kind A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1
agent dispersion carboxy-containing Content 44 44 44 44 44 44 44 44
paste polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1 D1-1
D1-1 D1-1 D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 60 60 60 Kind
D1-2 D1-2 D1-2 D1-2 D1-2 D1-2 D1-2 D1-2 Content 1 1 1 1 1 1 1 1
Extender pigment Kind D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 (D2)
Content 15 15 15 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2 D2-2
D2-2 D2-2 Content 3 3 3 3 3 3 3 3 Hydroxy- and carboxy-containing
Kind A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1
polyester resin (A3-1) Content 98 98 98 98 98 98 98 98 Diester
compound (C) Kind C-9 C-10 C-11 C-12 C-13 C-14 C-15 C-16 Content 10
10 10 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1
E-1 E-1 E-1 E-1 Content 10 10 10 10 10 10 10 10 Curing
Polyisocyanate compound (B1) Kind B1-1 B1-1 B1-1 B1-1 B1-1 B1-1
B1-1 B1-1 agent Content 26 26 26 26 26 26 26 26 Gel fraction
(G.sub.80) of the coating film after being 39 41 40 38 39 42 41 40
heated at 80.degree. C. for 10 minutes [%]
TABLE-US-00005 TABLE 5 Production Example 1-32 1-33 1-34 1-35 1-36
1-37 1-38 Aqueous intermediate coating composition (X1) X1-17 X1-18
X1-19 X1-20 X1-21 X1-22 X1-23 Main Pigment Hydroxy- and Kind A3-1-1
A3-1-1 A3-1-2 A3-1-3 A3-1-4 A3-1-5 A3-1-6 agent dispersion
carboxy-containing Content 44 44 44 44 44 44 44 paste polyester
resin (A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1 D1-1 D1-1
D1-1 (D1) Content 60 60 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 D1-2 D1-2 Content 1 1 1 1 1 1 1 Extender pigment Kind D2-1
D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 (D2) Content 15 15 15 15 15 15 15
Kind D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 Content 3 3 3 3 3 3 3
Hydroxy- and carboxy-containing Kind A3-1-1 A3-1-1 A3-1-2 A3-1-3
A3-1-4 A3-1-5 A3-1-6 polyester resin (A3-1) Content 98 98 98 98 98
98 98 Diester compound (C) Kind C-17 C-18 C-8 C-8 C-8 C-8 C-8
Content 10 10 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1 E-1
E-1 E-1 E-1 E-1 E-1 Content 10 10 10 10 10 10 10 Curing
Polyisocyanate compound (B1) Kind B1-1 B1-1 B1-1 B1-1 B1-1 B1-1
B1-1 agent Content 26 26 26 26 26 26 26 Gel fraction (G.sub.80) of
the coating film after being 38 42 41 40 39 42 38 heated at
80.degree. C. for 10 minutes [%]
TABLE-US-00006 TABLE 6 Production Example 1-39 1-40 1-41 1-42 1-43
1-44 Aqueous intermediate coating composition (X1) X1-24 X1-25
X1-26 X1-27 X1-28 X1-29 Main Pigment Hydroxy- and Kind A3-1-7
A3-1-8 A3-1-9 A3-1-10 A3-1-11 A3-1-12 agent dispersion
carboxy-containing Content 44 44 44 44 44 44 paste polyester resin
(A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1 D1-1 D1-1 (D1)
Content 60 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2 D1-2 D1-2
Content 1 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
D2-2 Content 3 3 3 3 3 3 Hydroxy- and carboxy-containing Kind
A3-1-7 A3-1-8 A3-1-9 A3-1-10 A3-1-11 A3-1-12 polyester resin (A3-1)
Content 98 98 98 98 98 98 Diester compound (C) Kind C-8 C-8 C-8 C-8
C-8 C-8 Content 10 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1
E-1 E-1 E-1 E-1 E-1 Content 10 10 10 10 10 10 Curing Polyisocyanate
compound (B1) Kind B1-1 B1-1 B1-1 B1-1 B1-1 B1-1 agent Content 26
26 26 26 26 26 Gel fraction (G.sub.80) of the coating film after
being 38 41 40 39 40 38 heated at 80.degree. C. for 10 minutes
[%]
TABLE-US-00007 TABLE 7 Production Example 1-45 1-46 1-47 1-48 1-49
Aqueous intermediate coating composition (X1) X1-30 X1-31 X1-32
X1-33 X1-34 Main Pigment Hydroxy- and Kind A3-1-1 A3-1-1 A3-1-1
A3-1-1 A3-1-1 agent dispersion carboxy-containing Content 44 44 44
44 44 paste polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1
D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 Content 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
Content 3 3 3 3 3 Hydroxy- and carboxy-containing Kind A3-1-1
A3-1-1 A3-1-1 A3-1-1 polyester resin (A3-1) Content 65 98 98 98
Hydroxy- and carboxy-containing Kind A3-2-1 A3-2-2 acrylic resin
(A3-2) Content 110 33 Diester compound (C) Kind C-8 C-8 C-8 C-8 C-8
Content 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1
E-1 Content 10 10 10 10 10 Curing Polyisocyanate compound (B1) Kind
B1-1 B1-1 B1-2 B1-3 B1-1 agent Content 26 26 26 33 16 Carbodilite
V-02 25 Gel fraction (G.sub.80) of the coating film after being 41
52 36 35 29 heated at 80.degree. C. for 10 minutes [%]
TABLE-US-00008 TABLE 8 Production Example 1-50 1-51 1-52 1-53 1-54
1-55 Aqueous intermediate coating composition (X1) X1-35 X1-36
X1-37 X1-38 X1-39 X1-40 Main Pigment Hydroxy- and Kind A3-1-1
A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 agent dispersion
carboxy-containing Content 44 44 44 44 44 44 paste polyester resin
(A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1 D1-1 D1-1 (D1)
Content 60 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2 D1-2 D1-2
Content 1 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
D2-2 Content 3 3 3 3 3 3 Hydroxy- and carboxy-containing Kind
A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 polyester resin (A3-1)
Content 98 98 98 98 98 98 Diester compound (C) Kind C-8 C-8 C-8 C-8
C-8 C-8 Content 10 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1
E-1 E-1 E-1 E-1 Content 10 10 10 10 10 Ethylene glycol mono-n-butyl
ether 10 Curing Polyisocyanate compound (B1) Kind B1-1 B1-1 B1-4
B1-1 B1-1 B1-1 agent Content 16 20 26 26 26 26 Kind B1-4 Content 6
Cymel 327 11 Gel fraction (G.sub.80) of the coating film after
being 20 45 41 38 38 39 heated at 80.degree. C. for 10 minutes
[%]
TABLE-US-00009 TABLE 9 Production Example 1-56 1-57 1-58 1-59 1-60
Aqueous intermediate coating composition (X1) X1-41 X1-42 X1-43
X1-44 X1-45 Main Pigment Hydroxy- and Kind A3-1-1 A3-1-1 A3-1-1
A3-1-1 A3-1-1 agent dispersion carboxy-containing Content 44 44 44
44 44 paste polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1
D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 Content 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
Content 3 3 3 3 3 Hydroxy- and carboxy-containing Kind A3-1-1
A3-1-1 A3-1-1 A3-1-1 A3-1-1 polyester resin (A3-1) Content 98 98
113 98 98 Diester compound (C) Kind C-19 C-20 C-8 C-8 Content 10 10
10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1 E-1 Content 10
10 10 10 10 Curing Polyisocyanate compound (B1) Kind B1-1 B1-1 B1-1
agent Content 26 26 29 Cymel 327 29 Bayhydrol VP LS-2310 68 Gel
fraction (G.sub.80) of the coating film after being 38 37 43 2 0
heated at 80.degree. C. for 10 minutes [%]
Production Example of Acrylic Resin Emulsion for an Aqueous Base
Coating Composition (Y)
Production Example 1-61
[0318] A 130 part quantity of deionized water and 0.52 parts of
Aqualon KH-10 were placed into a reaction vessel equipped with a
thermometer, a thermostat, a stirrer, a reflux condenser, a
nitrogen inlet tube and a dropping funnel, stirred and mixed in a
nitrogen flow, and heated to 80.degree. C. Subsequently, 1% of the
total amount of the emulsified monomer (1) described below and 5.3
parts of 6% ammonium persulfate solution were introduced into the
reaction vessel and maintained at 80.degree. C. for 15 minutes. The
remaining emulsified monomer (1) was then added dropwise into a
reaction vessel over 3 hours where the reaction vessel was
maintained at the same temperature. After completion of the
dropwise addition, the reaction product was aged for 1 hour.
Subsequently, the emulsified monomer (2) described below was added
dropwise over 1 hour. After aging for 1 hour, the reaction product
was cooled to 30.degree. C. while gradually adding 40 parts of 5%
dimethylethanolamine solution into a reaction vessel, and filtrated
using 100-mesh nylon cloth to obtain a filtrate of acrylic resin
emulsion (AC) having a mean particle diameter of 100 nm and a
solids content of 30%.
[0319] After diluting the emulsion with deionized water, the mean
particle diameter was measured using the submicron particle size
distribution analyzer ("COULTER N4", a product of Beckman Coulter,
Inc.) at 20.degree. C.
[0320] The resulting acrylic resin had an acid value of 33 mg KOH/g
and a hydroxy value of 25 mg KOH/g.
[0321] Emulsified monomer (1): 42 parts of deionized water, 0.72
parts of Aqualon KH-10, 2.1 parts of methylene-bis-acrylamide, 2.8
parts of styrene, 16.1 parts of methyl methacrylate, 28 parts of
ethyl acrylate and 21 parts of n-butyl acrylate were mixed under
stirring to obtain an emulsified monomer (1).
[0322] Emulsified monomer (2): 18 parts of deionized water, 0.31
parts of Aqualon KH-10, 0.03 parts of ammonium persulfate, 5.1
parts of methacrylic acid, 5.1 parts of 2-hydroxyethyl acrylate, 3
parts of styrene, 6 parts of methyl methacrylate, 1.8 parts of
ethyl acrylate and 9 parts of n-butyl acrylate were mixed under
stirring to obtain an emulsified monomer (2).
Production of Polyester Resin for an Aqueous Base Coating
Composition (Y)
Production Example 1-62
[0323] A 109 part quantity of trimethylolpropane, 141 parts of
1,6-hexanediol, 126 parts of hexahydrophthalic anhydride and 120
parts of adipic acid were placed into a reaction vessel equipped
with a thermometer, a thermostat, a stirrer, a reflux condenser and
a water separator, and were heated from 160.degree. C. to
230.degree. C. over 3 hours, followed by a condensation reaction at
230.degree. C. for 4 hours. Subsequently, in order to add a
carboxyl group to the resulting condensation reaction product, 38.3
parts of trimellitic anhydride was further added, and allowed to
react at 170.degree. C. for 30 minutes. The reaction product was
diluted with 2-ethyl-1-hexanol (mass dissolved in 100 g of water at
20.degree. C.: 0.1 g) to obtain a polyester resin solution (9E1)
with a solid content of 70%. The resulting polyester resin had an
acid value of 46 mg KOH/g, a hydroxy value of 150 mg KOH/g, and a
weight average molecular weight of 6,400.
Production Example 1-63
[0324] A polyester resin solution (PE2) was obtained in the same
manner as in Production Example 1-62, except that ethylene
glycolmono-n-butyl ether (mass dissolved in 100 g of water at
20.degree. C.: unlimited) was used in place of
2-ethyl-1-hexanol.
Production Example of Luster Pigment Dispersion
Production Example 1-64
[0325] In a stirring and mixing container, 19 parts of an aluminium
pigment paste (trade name "GX-180A", produced by Asahi Kasei Metals
Co., Ltd., metal content: 74%), 35 parts of 2-ethyl-1-hexanol, 8
parts of a phosphoric acid-containing resin solution (refer to Note
1 below) and 0.2 parts of 2-(dimethylamino)ethanol were
homogenously mixed to obtain a luster pigment dispersion (P1).
[0326] Note 1: The phosphoric acid-containing resin solution was
prepared as follows. A solvent mixture comprising 27.5 parts of
methoxypropanol and 27.5 parts of isobutanol was put into a
reaction vessel equipped with a thermometer, a thermostat, a
stirrer, a reflux condenser, a nitrogen inlet tube and a dropping
funnel, and then heated to 110.degree. C. Subsequently, 121.5 parts
of a mixture comprising 25 parts of styrene, 27.5 parts of n-butyl
methacrylate, 20 parts of branched higher alkyl acrylate (trade
name: "isostearyl acrylate", product of Osaka Organic Chemical
Industry, Ltd.), 7.5 parts of 4-hydroxybutyl acrylate, 15 parts of
a phosphoric acid-containing polymerizable monomer (refer to Note 2
below), 12.5 parts of 2-methacryloyloxy ethyl acid phosphate, 10
parts of isobutanol and 4 parts of t-butyl peroxyoctanoate were
added to the above solvent mixture over 4 hours. Subsequently, a
mixture comprising 0.5 parts of t-butyl peroxyoctanoate and 20
parts of isopropanol was added dropwise to the mixture obtained as
above over 1 hour. Subsequently, the resulting mixture was aged
over 1 hour with stirring to obtain a phosphoric acid-containing
resin solution with a solid content of 50%. The phosphoric
acid-containing resin had an acid value of 83 mg KOH/g based on the
phosphoric acid group, a hydroxy value of 29 mg KOH/g, and a weight
average molecular, weight of 10,000.
[0327] Note 2: The phosphoric acid-containing polymerizable monomer
was prepared as follows. 57.5 parts of monobutyl phosphate and 41
parts of isobutanol were put into a reaction vessel equipped with a
thermometer, a thermostat, a stirrer, a reflux condenser, a
nitrogen inlet tube and a dropping funnel, and were heated to
90.degree. C. Subsequently, 42.5 parts of glycidyl methacrylate was
added dropwise over 2 hours. After aging for 1 hour with stirring,
59 parts of isopropanol was added to obtain a phosphoric
acid-containing polymerizable monomer solution with a solid content
of 50%. The resulting monomer had an acid value of 285 mg KOH/g
based on the phosphoric acid group.
Production Example 1-65
[0328] A luster pigment dispersion (P2) was obtained in the same
manner as in Production Example 1-64, except that ethylene
glycolmono-n-butyl ether was used in place of
2-ethyl-1-hexanol.
Production of an Aqueous Base Coating Composition (Y)
Production Example 1-66
[0329] A 100 part quantity of the acrylic resin emulsion (AC)
obtained in Production Example 1-61, 57 parts of the polyester
resin solution (PE1) obtained in Production Example 1-62, 62 parts
of the luster pigment dispersion (P1) obtained in Production
Example 1-64 and 37.5 parts of the melamine resin (trade name
"Cymel 325", produced by Japan Cytec Industries, Inc., solids
content: 80%) were homogenously mixed, and a polyacrylic acid
thickening agent (trade name "Primal ASE-60", produced by Rohm and
Haas), 2-(dimethylamino)ethanol and deionized water were further
added to obtain an aqueous base coating composition (Y-1) having a
pH of 8.0, a solids content of 25%, and a viscosity of 40 seconds
as measured at 20.degree. C. using Ford Cup No. 4.
Production Example 1-67
[0330] A 100 part quantity of the acrylic resin emulsion (AC)
obtained in Production Example 1-61, 57 parts of the polyester
resin solution (PE2) obtained in Production Example 1-63, 62 parts
of the luster pigment dispersion (P2) obtained in Production
Example 1-65 and 37.5 parts of melamine resin (trade name "Cymel
325", produced by Japan Cytec Industries, Inc., solids content:
80%) were homogenously mixed, and a polyacrylic acid thickening
agent (trade name "Primal ASE-60", produced by Rohm and Haas),
2-(dimethylamino)ethanol and deionized water were further added to
obtain an aqueous base coating composition (Y-2) having a pH of
8.0, a solids content of 25%, and a viscosity of 40 seconds as
measured at 20.degree. C. using Ford Cup No. 4.
Preparation of Test Plate
[0331] The aqueous intermediate coating compositions (X1-1) to
(X1-45) obtained in Production Examples 1-16 to 1-60, and the
aqueous base coating compositions (Y-1) and (Y-2) obtained in
Production Examples 1-66 and 1-67 were used in the following manner
to form test plates. Evaluation tests were then performed.
Preparation of Test Substrate to be Coated
[0332] A cationic electrodeposition coating composition (trade name
"Electron GT-10", produced by Kansai Paint Co., Ltd.) was applied
to a cold-rolled steel plate treated with zinc phosphate by
electrodeposition to a cured film thickness of 20 .mu.m, and was
cured by heating at 170.degree. C. for 30 minutes. A test substrate
to be coated was thus prepared.
Example 1-1
[0333] The aqueous intermediate coating composition (X1-1) obtained
in Production Example 1-16 was electrostatically applied to the
substrate to a cured film thickness of 25 .mu.m using a rotary
atomizing electrostatic coating machine. The substrate was then
allowed to stand for 2 minutes, and preheated at 80.degree. C. for
3 minutes. Subsequently, the aqueous base coating composition (Y-1)
obtained in Production Example 1-66 was electrostatically applied
to the uncured intermediate coating film to a cured film thickness
of 15 .mu.m using a rotary atomizing electrostatic coating machine,
then allowed to stand for 2 minutes, and preheated at 80.degree. C.
for 3 minutes. Next, an acrylic resin solvent-based clear topcoat
composition (trade name "Magicron KINO-1210", produced by Kansai
Paint Co., Ltd.; hereinafter sometimes referred to as "clear
coating composition (Z-1)") was electrostatically applied to the
uncured base coating film to a cured film thickness of 35 .mu.m,
then allowed to stand for 7 minutes, and heated at 140.degree. C.
for minutes to cure the intermediate coating film, the base coating
film and the clear coating film simultaneously. A test plate was
thus obtained.
Examples 1-2 to 1-41, Comparative Examples 1-1 to 1-5
[0334] Test plates were obtained in the same manner as in Example
1-1, except that any one of the aqueous intermediate coating
compositions (X1-2) to (X1-45) shown in Tables 10 to 14 was used in
place of the aqueous intermediate coating composition (X1-1)
obtained in Production Example 1-16, and that the aqueous base
coating composition (Y-1) shown in Tables 10 to 14, or the aqueous
base coating composition (Y-2) obtained in Production Example 1-67
was used in place of the aqueous base coating composition (Y-1)
obtained in Production Example 1-66.
Evaluation Test
[0335] Test plates obtained in Examples 1-1 to 1-41 and Comparative
Examples 1-1 to 1-5 were evaluated according to the test method
below. Tables 10 to 14 show the evaluation results.
Test Method
[0336] Smoothness: Smoothness was evaluated based on the Long Wave
(LW) values that were measured by "Wave Scan" (produced by BYK
Gardner). The smaller the Long Wave (LW) value, the higher the
smoothness of the coating surface. In Tables 10 to 14, "initial"
indicates the smoothness of the aqueous intermediate coating
composition (X1) coated immediately after production, and
"post-storage" indicates the smoothness of the coated aqueous
intermediate composition (X1) obtained by mixing the main agent
that is stored at 30.degree. C. for 30 days after the production,
with other raw materials.
[0337] Distinctness of image: Distinctness of image was evaluated
based on the Short Wave (SW) values measured by the "Wave Scan".
The smaller the Short Wave (SW) value, the higher the distinctness
of image on the coating surface.
[0338] Flip-flop effect: Test plates were observed visually from
various angles, and a flip-flop effect was rated according to the
following criteria.
[0339] A: There were significant changes in the metallic appearance
visually observed (exceedingly excellent flip-flop effect);
[0340] B: There were large changes in the metallic appearance
visually observed (excellent flip-flop effect);
[0341] C: There was relatively little change in the metallic
appearance visually observed (slightly poor flip-flop effect);
and
[0342] D: There was little change in the metallic appearance
visually observed (poor flip-flop effect).
[0343] Metallic mottling: Test plates were visually observed, and
the occurrence of metallic mottling was rated according to the
following criteria.
[0344] A: Almost no metallic mottling was observed, and the coating
film had an extremely excellent appearance;
[0345] B: A small amount of metallic mottling was observed, but the
coating film had an excellent appearance;
[0346] C: Metallic mottling was observed, and the coating film had
a relatively poor appearance; and
[0347] D: A considerable amount of metallic mottling was observed,
and the coating film had a poor appearance.
[0348] Water resistance: Test plates were immersed in warm water at
40.degree. C. for 240 hours and removed therefrom, and then dried
at 20.degree. C. for 12 hours. Lattice-like cuts were made in the
multilayer coating films on the test plates in a manner such that a
knife reaches the base material, making 100 crosscuts having a size
of 2 mm.times.2 mm. Subsequently, an adhesive cellophane tape was
adfixed to their surfaces, and the tape was abruptly peeled off at
20.degree. C. The conditions of the remaining crosscut coating
films were checked.
[0349] A: 100 crosscut sections of the coating film remained, and
no small chipped edges were produced at the cutting edges made by
the cutter knife;
[0350] B: 100 crosscut sections of the coating film remained, but
small chipped edges were observed at the cutting edges made by the
cutter knife;
[0351] C: 90 to 99 crosscut sections of the coating film remained;
and
[0352] D: The number of remaining crosscut sections of the coating
film was 89 or less.
[0353] Chipping resistance: A test plate was fixed on the sample
holder of a gravel chipping test instrument (trade name "JA-400",
produced by Suga Test Instruments Co., Ltd.,) and 50 g of granite
gravel of No. 7 particle size was sprayed at a distance of 30 cm
from the test plate and at an angle of 45.degree. onto the test
plate with compressed air at 0.392 MPa (4 kgf/cm.sup.2) at
-20.degree. C. Subsequently, the resulting test plate was washed
with water and dried. A cloth adhesive tape (a product of Nichiban
Co., Ltd.) was applied to the coating surface, and then peeled off.
The degree of the occurrence of the scratches formed on the coating
film was visually observed and evaluated.
[0354] A: Sizes of scratches were exceedingly small, and the
electrodeposition surface and the substrate of the steel plate were
not exposed.
[0355] B: Sizes of scratches were small, and the electrodeposition
surface and the substrate of the steel plate were not exposed.
[0356] C: Sizes of scratches were small, but the electrodeposition
surface or the substrate of the steel plate was exposed.
[0357] D: Sizes of scratches were considerably large, and the
substrate of the steel plate was largely exposed.
TABLE-US-00010 TABLE 10 Example 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9
1-10 Aqueous intermediate X1-1 X1-2 X1-3 X1-4 X1-5 X1-6 X1-7 X1-8
X1-9 X1-10 coating composition (X1) Aqueous base coating Y-1 Y-1
Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 composition (Y) Clear coating Z-1
Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 composition (Z) Evaluation
result Smoothness Initial 8.1 8.2 7.5 7.7 7.0 7.3 7.7 7.2 7.3 7.4
Post- 9.3 8.6 7.9 8.2 8.1 8.3 8.8 7.5 8.1 7.9 storage Distinctness
of image 15.4 15.2 13.8 14.3 13.4 13.6 13.8 13.2 13.8 13.6
Flip-flop effect B A A A A B B A A A Metallic mottling B A A A A A
B A A A Water resistance B A A A A A A A A A Chipping resistance A
A A A A A A A A A
TABLE-US-00011 TABLE 11 Example 1-11 1-12 1-13 1-14 1-15 1-16 1-17
1-18 1-19 1-20 Aqueous intermediate X1-11 X1-12 X1-13 X1-14 X1-15
X1-16 X1-17 X1-18 X1-19 X1-20 coating composition (X1) Aqueous base
coating Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 composition (Y)
Clear coating Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 composition
(Z) Evaluation result Smoothness Initial 7.9 8.1 8.3 8.4 8.3 7.2
8.3 8.5 7.4 7.2 Post- 9.3 8.5 9.3 9.4 8.7 7.6 8.4 9.5 7.9 7.7
storage Distinctness of image 14.4 15.0 15.5 15.8 15.6 13.7 15.4
15.8 13.5 13.2 Flip-flop effect A A B B B A B B A A Metallic
mottling B A B B B A A B A A Water resistance A A B B B A B B A A
Chipping resistance A A A A A A A A A A
TABLE-US-00012 TABLE 12 Example 1-21 1-22 1-23 1-24 1-25 1-26 1-27
1-28 1-29 1-30 Aqueous intermediate X1-21 X1-22 X1-23 X1-24 X1-25
X1-26 X1-27 X1-28 X1-29 X1-30 coating composition (X1) Aqueous base
coating Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 composition (Y)
Clear coating Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Composition
(Z) Evaluation result Smoothness Initial 7.2 6.8 6.4 6.7 6.2 7.8
8.3 8.5 7.7 8.3 Post- 7.6 7.3 6.9 7.2 6.6 8.3 8.8 9.1 8.3 8.8
storage Distinctness of image 12.9 13.1 12.8 13.1 12.9 14.2 15.3
15.9 13.8 12.8 Flip-flop effect A A A A A A A A A A Metallic
mottling A A A A A A A A A A Water resistance A A A A A A B B A A
Chipping resistance A A A A A B A A B B
TABLE-US-00013 TABLE 13 Example 1-31 1-32 1-33 1-34 1-35 1-36 1-37
1-38 1-39 1-40 1-41 Aqueous intermediate X1-31 X1-32 X1-33 X1-34
X1-35 X1-36 X1-37 X1-38 X1-39 X1-40 X1-8 coating composition (X1)
Aqueous base coating Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-2
composition (Y) Clear coating Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1
Z-1 Z-1 composition (Z) Evaluation result Smoothness Initial 9.1
7.3 7.5 7.3 9.4 8.2 8.9 9.4 9.5 9.4 8.2 Post- 9.5 7.8 8.0 7.8 9.9
8.8 9.4 9.8 9.9 9.9 8.7 storage Distinctness of image 13.2 13.6
14.2 14.1 15.9 13.1 13.2 12.9 13.0 12.8 14.1 Flip-flop effect A A A
B B A A A A B B Metallic mottling A A A B B A A A A B B Water
resistance A A B A A A A A B A A Chipping resistance A A A B B A A
A A A A
TABLE-US-00014 TABLE 14 Comparative Example 1-1 1-2 1-3 1-4 1-5
Aqueous intermediate X1-41 X1-42 X1-43 X1-44 X1-45 coating
composition (X1) Aqueous base coating Y-1 Y-1 Y-1 Y-1 Y-1
composition (Y) Clear coating Z-1 Z-1 Z-1 Z-1 Z-1 Composition (Z)
Evaluation result Smoothness Initial 11.1 13.1 11.5 12.2 12.5 Post-
12.1 13.3 11.9 12.8 13.0 storage Distinctness of image 17.7 17.1
18.4 19.4 19.1 Flip-flop effect C C C C C Metallic mottling D D C C
C Water resistance A A A A A Chipping resistance A A A A A
Production of Aqueous Intermediate Coating Composition (X2)
Production Example 2-1
[0358] A 44 part quantity (resin solids content: 20 parts) of
aqueous hydroxy- and carboxy-containing polyester resin dispersion
(A3-1-1) obtained in Production Example 1-1, 60 parts of rutile
titanium dioxide (D1-1) (trade name "JR-806", produced by TAYCA
CORP.), 1 part of carbon black (D1-2) (trade name "Carbon MA-100",
produced by Mitsubishi Chemical, Inc.), 15 parts of barium sulfate
powder (D2-1) (trade name "Bariace B-35", produced by Sakai
Chemical Industry Co., Ltd.) having an average primary particle
diameter of 0.5 .mu.m, 3 parts of powdered talc (D2-2) (trade name
"MICRO ACE S-3", produced by Nippon Talc Co., Ltd) having an
average primary particle diameter of 4.8 .mu.m, and 11 parts of
deionized water were mixed. After being adjusted to a pH of 8.0
with 2-(dimethylamino)ethanol, the mixture was dispersed using a
paint shaker for 30 minutes to obtain a pigment dispersion
paste.
[0359] Next, 134 parts of the resulting pigment dispersion paste,
89 parts of aqueous hydroxy- and carboxy-containing polyester resin
dispersion (A3-1-1) obtained in Production Example 1-1, 10 parts of
the diester compound (C-1) used in Production Example 1-16, and 10
parts of hydrophobic solvent (E-1) (2-ethyl-1-hexanol (mass
dissolved in 100 g of water at 20.degree. C.: 0.1 g)) were
homogeneously mixed to obtain a main agent.
[0360] Subsequently, 38 parts of polycarbodiimide compound (B2-1)
(trade name "Carbodilite SV-02" produced by Nisshinbo Industries,
Inc., solids content 40%), 19 parts of melamine resin (B3-1) (a
methyl-butyl-etherified melamine resin, molar ratio of
methoxy/butoxy=70/30, weight average molecular weight: 700, solids
content: 80%), a urethane associative thickening agent (trade name
"UH-752", produced by ADEKA Co., Ltd.), 2-(dimethylamino)ethanol,
and deionized water were added to the resulting main agent, to
obtain an aqueous intermediate coating composition (X2-1) having a
pH of 8.0, a solids content of 48%, and a viscosity of 40 seconds
as measured at 20.degree. C. using Ford Cup No. 4. The application
was conducted so that the resulting aqueous intermediate coating
composition (X2-1) had a cured film thickness of 30 .mu.m, and the
gel fraction (G.sub.80) of the coating film after being heated at
80.degree. C. for 10 minutes was 32%.
Production Examples 2-2 to 2-36, and 2-39 to 2-43
[0361] According to the proportions shown in Tables 15 to 21 below,
aqueous intermediate coating compositions (X2-2) to (X2-36) and
(X2-39) to (X2-43), each having a pH of 8.0, solids content of 48%,
and a viscosity of 40 seconds as measured at 20.degree. C. using
Ford Cup No. 4 were obtained in the same manner as in Production
Example 2-1.
[0362] In Production Example 2-36, 10 parts of ethylene glycol
mono-n-butyl ether (mass dissolved in 100 g of water at 20.degree.
C.: unlimited) was added in place of the hydrophobic solvent (E-1).
In Production Example 2-43, 68 parts of a blocked polyisocyanate
compound (trade name "Bayhydrol VPLS2310", produced by Sumika Bayer
Urethane Co., Ltd., solids content: 38%) was added during the
production of the aqueous intermediate coating composition
(X2).
[0363] Polycarbodiimide compound (B2-2) represented in Table 19
below is as follows.
[0364] Polycarbodiimide Compound (B2-2): Carbodilite V-02 produced
by Nisshinbo Industries, Inc., solids content: 40%)
[0365] Diester compounds (C-2 to C-20) represented in Tables 15 to
21 are the same as above.
[0366] Melamine resins (B3-2 and B3-3) represented in Table 20 are
as follows.
[0367] Melamine resin (B3-2): a methyl-etherified melamine resin,
molar ratio of methoxy/butoxy=100/0, weight average molecular
weight: 650, solids content: 90%)
[0368] Melamine resin (B3-3): a methyl-butyl-etherified melamine
resin, molar ratio of methoxy/butoxy=55/45, weight average
molecular weight: 1200, solids content: 70%)
Production Example 2-37
[0369] A 44 part quantity (resin solids content: 20 parts) of
aqueous hydroxy- and carboxy-containing polyester resin dispersion
(A3-1-1) obtained in Production Example 1-1, 60 parts of rutile
titanium dioxide (D1-1), 1 part of carbon black (D1-2), 15 parts of
barium sulfate powder (D2-1) having an average primary particle
diameter of 0.5 .mu.m, 3 parts of powdered talc (D2-2) having an
average primary particle diameter of 4.8 .mu.m, and 11 parts of
deionized water were mixed. After being adjusted to a pH of 8.0
with 2-(dimethylamino)ethanol, the mixture was dispersed using a
paint shaker for 30 minutes to obtain a pigment dispersion
paste.
[0370] Next, 134 parts of the resulting pigment dispersion paste,
89 parts of aqueous hydroxy- and carboxy-containing polyester resin
dispersion (A3-1-1) obtained in Production Example 1-1, 10 parts of
diester compound (C-8), and 10 parts of hydrophobic solvent (E-1)
were homogeneously mixed to obtain a main agent.
[0371] Subsequently, 38 parts of polycarbodiimide compound (B2-1),
19 parts of melamine resin (B3-1), a polyacrylic acid thickening
agent (trade name "PRIMAL ASE-60", produced by Rohm and Haas),
2-(dimethylamino)ethanol, and deionized water were added to the
resulting main agent, to obtain an aqueous intermediate coating
composition (X2-37) having a pH of 8.0, a solids content of 48%,
and a viscosity of 40 seconds as measured at 20.degree. C. using
Ford Cup No. 4.
Production Example 2-38
[0372] A 44 part quantity (resin solids content: 20 parts) of
aqueous hydroxy- and carboxy-containing polyester resin dispersion
(A3-1-1) obtained in Production Example 1-1, 60 parts of rutile
titanium dioxide (D1-1), 1 part of carbon black (D1-2), 15 parts of
barium sulfate powder (D2-1) having an average primary particle
diameter of 0.5 .mu.m, 3 parts of powdered talc (D2-2) having an
average primary particle diameter of 4.8 .mu.m, and 11 parts of
deionized water were mixed. After being adjusted to a pH of 8.0
with 2-(dimethylamino)ethanol, the mixture was dispersed using a
paint shaker for 30 minutes to obtain a pigment dispersion
paste.
[0373] Next, 134 parts of the resulting pigment dispersion paste,
89 parts of aqueous hydroxy- and carboxy-containing polyester resin
dispersion (A3-1-1) obtained in Production Example 1-1, 10 parts of
diester compound (C-8), and 10 parts of hydrophobic solvent (E-1)
were homogeneously mixed to obtain a main agent.
[0374] Subsequently, 38 parts of polycarbodiimide compound (B2-1),
19 parts of melamine resin (B3-1), 2-(dimethylamino)ethanol, and
deionized water were added to the resulting main agent, to obtain
an aqueous intermediate coating composition (X2-38) having a pH of
8.0 and a viscosity of 40 seconds as measured at 20.degree. C.
using Ford Cup No. 4.
TABLE-US-00015 TABLE 15 Production Example 2-1 2-2 2-3 2-4 2-5 2-6
2-7 Aqueous intermediate coating composition (X2) X2-1 X2-2 X2-3
X2-4 X2-5 X2-6 X2-7 Main Pigment Hydroxy- and Kind A3-1-1 A3-1-1
A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 agent dispersion
carboxy-containing Content 44 44 44 44 44 44 44 paste polyester
resin (A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1 D1-1 D1-1
D1-1 (D1) Content 60 60 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 D1-2 D1-2 Content 1 1 1 1 1 1 1 Extender pigment Kind D2-1
D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 (D2) Content 15 15 15 15 15 15 15
Kind D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 Content 3 3 3 3 3 3 3
Hydroxy- and carboxy-containing Kind A3-1-1 A3-1-1 A3-1-1 A3-1-1
A3-1-1 A3-1-1 A3-1-1 polyester resin (A3-1) Content 89 89 89 89 89
89 89 Diester compound (C) Kind C-1 C-2 C-3 C-4 C-5 C-6 C-7 Content
10 10 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1
E-1 E-1 E-1 Content 10 10 10 10 10 10 10 Curing Polycarbodiimido
compound (B2) Kind B2-1 B2-1 B2-1 B2-1 B2-1 B2-1 B2-1 agent Content
38 38 38 38 38 38 38 Melamine resin (B3) Kind B3-1 B3-1 B3-1 B3-1
B3-1 B3-1 B3-1 Content 19 19 19 19 19 19 19 Gel fraction (G.sub.80)
of the coating film after being 32 31 30 34 33 33 34 heated at
80.degree. C. for 10 minutes [%]
TABLE-US-00016 TABLE 16 Production Example 2-8 2-9 2-10 2-11 2-12
2-13 2-14 2-15 Aqueous intermediate coating composition (X2) X2-8
X2-9 X2-10 X2-11 X2-12 X2-13 X2-14 X2-15 Main Pigment Hydroxy- and
Kind A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 agent
dispersion carboxy-containing Content 44 44 44 44 44 44 44 44 paste
polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1
D1-1 D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 60 60 60 Kind D1-2
D1-2 D1-2 D1-2 D1-2 D1-2 D1-2 D1-2 Content 1 1 1 1 1 1 1 1 Extender
pigment Kind D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 (D2) Content
15 15 15 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 D2-2
D2-2 Content 3 3 3 3 3 3 3 3 Hydroxy- and carboxy-containing Kind
A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 A3-1-1 polyester
resin (A3-1) Content 89 89 89 89 89 89 89 89 Diester compound (C)
Kind C-8 C-9 C-10 C-11 C-12 C-13 C-14 C-15 Content 10 10 10 10 10
10 10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1 E-1 E-1 E-1
E-1 Content 10 10 10 10 10 10 10 10 Curing Polycarbodiimido
compound (B2) Kind B2-1 B2-1 B2-1 B2-1 B2-1 B2-1 B2-1 B2-1 agent
Content 38 38 38 38 38 38 38 38 Melamine resin (B3) Kind B3-1 B3-1
B3-1 B3-1 B3-1 B3-1 B3-1 B3-1 Content 19 19 19 19 19 19 19 19 Gel
fraction (G.sub.80) of the coating film after being 30 31 33 32 30
31 34 33 heated at 80.degree. C. for 10 minutes [%]
TABLE-US-00017 TABLE 17 Production Example 2-16 2-17 2-18 2-19 2-20
2-21 2-22 Aqueous intermediate coating composition (X2) X2-16 X2-17
X2-18 X2-19 X2-20 X2-21 X2-22 Main Pigment Hydroxy- and Kind A3-1-1
A3-1-1 A3-1-1 A3-1-2 A3-1-3 A3-1-4 A3-1-5 agent dispersion
carboxy-containing Content 44 44 44 44 44 44 44 paste polyester
resin (A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1 D1-1 D1-1
D1-1 (D1) Content 60 60 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 D1-2 D1-2 Content 1 1 1 1 1 1 1 Extender pigment Kind D2-1
D2-1 D2-1 D2-1 D2-1 D2-1 D2-1 (D2) Content 15 15 15 15 15 15 15
Kind D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 D2-2 Content 3 3 3 3 3 3 3
Hydroxy- and carboxy-containing Kind A3-1-1 A3-1-1 A3-1-1 A3-1-2
A3-1-3 A3-1-4 A3-1-5 polyester resin (A3-1) Content 89 89 89 89 89
89 89 Diester compound (C) Kind C-16 C-17 C-18 C-8 C-8 C-8 C-8
Content 10 10 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1 E-1
E-1 E-1 E-1 E-1 E-1 Content 10 10 10 10 10 10 10 Curing
Polycarbodiimido compound (B2) Kind B2-1 B2-1 B2-1 B2-1 B2-1 B2-1
B2-1 agent Content 38 38 38 38 38 38 38 Melamine resin (B3) Kind
B3-1 B3-1 B3-1 B3-1 B3-1 B3-1 B3-1 Content 19 19 19 19 19 19 19 Gel
fraction (G.sub.80) of the coating film after being 32 30 34 33 32
31 34 heated at 80.degree. C. for 10 minutes [%]
TABLE-US-00018 TABLE 18 Production Example 2-23 2-24 2-25 2-26 2-27
2-28 Aqueous intermediate coating composition (X2) X2-23 X2-24
X2-25 X2-26 X2-27 X2-28 Main Pigment Hydroxy- and Kind A3-1-6
A3-1-7 A3-1-8 A3-1-9 A3-1-10 A3-1-11 agent dispersion
carboxy-containing Content 44 44 44 44 44 44 paste polyester resin
(A3-1) Coloring pigment Kind D1-1 D1-1 D1-1 D1-1 D1-1 D1-1 (D1)
Content 60 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2 D1-2 D1-2
Content 1 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
D2-2 Content 3 3 3 3 3 3 Hydroxy- and carboxy-containing Kind
A3-1-6 A3-1-7 A3-1-8 A3-1-9 A3-1-10 A3-1-11 polyester resin (A3-1)
Content 89 89 89 89 89 89 Diester compound (C) Kind C-8 C-8 C-8 C-8
C-8 C-8 Content 10 10 10 10 10 10 Hydrophobic solvent (E) Kind E-1
E-1 E-1 E-1 E-1 E-1 Content 10 10 10 10 10 10 Curing
Polycarbodiimido compound (B2) Kind B2-1 B2-1 B2-1 B2-1 B2-1 B2-1
agent Content 38 38 38 38 38 38 Melamine resin (B3) Kind B3-1 B3-1
B3-1 B3-1 B3-1 B3-1 Content 19 19 19 19 19 19 Gel fraction
(G.sub.80) of the coating film after being 31 30 33 32 31 32 heated
at 80.degree. C. for 10 minutes [%]
TABLE-US-00019 TABLE 19 Production Example 2-29 2-30 2-31 2-32 2-33
Aqueous intermediate coating composition (X2) X2-29 X2-30 X2-31
X2-32 X2-33 Main Pigment Hydroxy- and Kind A3-1-12 A3-1-1 A3-1-1
A3-1-1 A3-1-1 agent dispersion carboxy-containing Content 44 44 44
44 44 paste polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1
D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 Content 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
Content 3 3 3 3 3 Hydroxy- and carboxy-containing Kind A3-1-12
A3-1-1 A3-1-1 polyester resin (A3-1) Content 89 100 89 Hydroxy- and
carboxy-containing Kind A3-2-1 A3-2-2 acrylic resin (A3-2) Content
100 89 Diester compound (C) Kind C-8 C-8 C-8 C-8 C-8 Content 10 10
10 10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1 E-1 Content
10 10 10 10 10 Curing Polycarbodiimido compound (B2) Kind B2-1 B2-1
B2-1 B2-1 B2-2 agent Content 38 38 38 63 38 Melamine resin (B3)
Kind B3-1 B3-1 B3-1 B3-1 Content 19 19 19 19 Gel fraction
(G.sub.80) of the coating film after being 30 33 42 20 28 heated at
80.degree. C. for 10 minutes [%]
TABLE-US-00020 TABLE 20 Production Example 2-34 2-35 2-36 2-37 2-38
Aqueous intermediate coating composition (X2) X2-34 X2-35 X2-36
X2-37 X2-38 Main Pigment Hydroxy- and Kind A3-1-1 A3-1-1 A3-1-1
A3-1-1 A3-1-1 agent dispersion carboxy-containing Content 44 44 44
44 44 paste polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1
D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 Content 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
Content 3 3 3 3 3 Hydroxy- and carboxy-containing Kind A3-1-1
A3-1-1 A3-1-1 A3-1-1 A3-1-1 polyester resin (A3-1) Content 89 89 89
89 89 Diester compound (C) Kind C-8 C-8 C-8 C-8 C-8 Content 10 10
10 10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1 Content 10 10
10 10 Ethylene glycol mono-n-butyl ether 10 Curing Polycarbodiimido
compound (B2) Kind B2-1 B2-1 B2-1 B2-1 B2-1 agent Content 38 38 38
38 38 Melamine resin (B3) Kind B3-2 B3-3 B3-1 B3-1 B3-1 Content 17
21 19 19 19 Gel fraction (G.sub.80) of the coating film after being
29 30 23 30 30 heated at 80.degree. C. for 10 minutes [%]
TABLE-US-00021 TABLE 21 Production Example 2-39 2-40 2-41 2-42 2-43
Aqueous intermediate coating composition (X2) X2-39 X2-40 X2-41
X2-42 X2-43 Main Pigment Hydroxy- and Kind A3-1-1 A3-1-1 A3-1-1
A3-1-1 A3-1-1 agent dispersion carboxy-containing Content 44 44 44
44 44 paste polyester resin (A3-1) Coloring pigment Kind D1-1 D1-1
D1-1 D1-1 D1-1 (D1) Content 60 60 60 60 60 Kind D1-2 D1-2 D1-2 D1-2
D1-2 Content 1 1 1 1 1 Extender pigment Kind D2-1 D2-1 D2-1 D2-1
D2-1 (D2) Content 15 15 15 15 15 Kind D2-2 D2-2 D2-2 D2-2 D2-2
Content 3 3 3 3 3 Hydroxy- and carboxy-containing Kind A3-1-1
A3-1-1 A3-1-1 A3-1-1 A3-1-1 polyester resin (A3-1) Content 89 89
104 98 98 Diester compound (C) Kind C-19 C-20 C-8 C-8 Content 10 10
10 10 Hydrophobic solvent (E) Kind E-1 E-1 E-1 E-1 E-1 Content 10
10 10 10 10 Curing Polycarbodiimido compound (B2) Kind B2-1 B2-1
B2-1 agent Content 38 38 41 Melamine resin (B3) Kind B3-1 B3-1 B3-1
B3-1 Content 19 19 21 33 Bayhydrol VP LS-2310 68 Gel fraction
(G.sub.80) of the coating film after being 30 30 34 2 0 heated at
80.degree. C. for 10 minutes [%]
Preparation of Test Plate
[0375] The aqueous intermediate coating compositions (X2-1) to
(X2-43) obtained in Production Examples 2-1 to 2-43, and the
aqueous base coating compositions (Y-1) and (Y-2) obtained in
Production Examples 1-66 and 1-67 were used in the following manner
to form test plates. Evaluation tests were then performed.
Preparation of Substrate to be Coated
[0376] A cationic electrodeposition coating composition (trade name
"Electron GT-10", produced by Kansai Paint Co., Ltd.) was applied
to a cold-rolled steel plate treated with zinc phosphate by
electrodeposition to a cured film thickness of 20 .mu.m, and was
cured by heating at 170.degree. C. for 30 minutes. A test substrate
was thus prepared.
Example 2-1
[0377] The aqueous intermediate coating composition (X2-1) obtained
in Production Example 2-1 was electrostatically applied to the
substrate using a rotary atomizing electrostatic coating machine to
a cured film thickness of 25 .mu.m, then allowed to stand for 2
minutes, and preheated at 80.degree. C. for 3 minutes.
Subsequently, the aqueous base coating composition (Y-1) obtained
in Production Example 1-66 was electrostatically applied to the
uncured intermediate coating film using a rotary atomizing
electrostatic coating machine to a cured film thickness of 15
.mu.m, then allowed to stand for 2 minutes, and preheated at
80.degree. C. for 3 minutes. Next, an acrylic resin solvent-based
clear topcoat composition (trade name "Magicron KINO-1210",
produced by Kansai Paint Co., Ltd; hereinafter sometimes referred
to as "clear coating composition (Z-1))" was electrostatically
applied to the uncured base coating film to a cured film thickness
of 35 pin, then allowed to stand for 7 minutes, and heated at
140.degree. C. for 30 minutes to cure the intermediate coating
film, the base coating film and the clear coating film
simultaneously. A test plate was thus obtained.
Examples 2-2 to 2-39, Comparative Examples 2-1 to 2-5
[0378] Test plates were obtained in the same manner as in Example
2-1, except that any one of aqueous intermediate coating
compositions (X2-2) to (X2-43) shown in Tables 22 to 26 was used in
place of the aqueous intermediate coating composition (X2-1)
obtained in Production Example 2-1, and that aqueous base coating
compositions shown in Tables 22 to 26 were used in place of the
aqueous base coating composition (Y-1) obtained in Production
Example 1-66.
Evaluation Test
[0379] Test plates obtained in Examples 2-1 to 2-39 and Comparative
Examples 2-1 to 2-5 were evaluated in the same manner as above for
smoothness, distinctness of image, flip-flop effect, metallic
mottling, water resistance, and chipping resistance. Tables 22 to
26 show the evaluation results.
TABLE-US-00022 TABLE 22 Example 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 2-9
2-10 Aqueous intermediate X2-1 X2-2 X2-3 X2-4 X2-5 X2-6 X2-7 X2-8
X2-9 X2-10 coating composition (X2) Aqueous base coating Y-1 Y-1
Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 composition (Y) Clear coating Z-1
Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Composition (Z) Evaluation
result Smoothness Initial 8.5 8.6 7.9 8.1 7.4 7.7 8.0 7.6 7.7 7.8
Post- 9.7 9.0 8.4 8.6 8.5 8.7 9.1 7.9 8.5 8.3 storage Distinctness
of image 16.3 16.1 14.6 15.1 14.2 14.4 14.7 13.6 14.6 14.4
Flip-flop effect B A A A A B B A A A Metallic mottling B A A A A A
B A A A Water resistance B A A A A A A A A A Chipping resistance A
A A A A A A A A A
TABLE-US-00023 TABLE 23 Example 2-11 2-12 2-13 2-14 2-15 2-16 2-17
2-18 2-19 2-20 Aqueous intermediate X2-11 X2-12 X2-13 X2-14 X2-15
X2-16 X2-17 X2-18 X2-19 X2-20 coating composition (X2) Aqueous base
coating Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 composition (Y)
Clear coating Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Composition
(Z) Evaluation result Smoothness Initial 8.3 8.5 8.7 8.8 8.7 7.6
8.7 8.9 7.8 7.6 Post- 9.7 8.9 9.7 9.8 9.1 8.0 8.8 9.9 8.3 8.1
storage Distinctness of image 15.2 15.9 16.4 16.7 16.5 14.5 16.3
16.7 13.9 13.6 Flip-flop effect A A B B B A B B A A Metallic
mottling B A B B B A A B A A Water resistance A A B B B A B B A A
Chipping resistance A A A A A A A A A A
TABLE-US-00024 TABLE 24 Example 2-21 2-22 2-23 2-24 2-25 2-26 2-27
2-28 2-29 2-30 Aqueous intermediate X2-21 X2-22 X2-23 X2-24 X2-25
X2-26 X2-27 X2-28 X2-29 X2-30 coating composition (X2) Aqueous base
coating Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 composition (Y)
Clear coating Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 composition
(Z) Evaluation result Smoothness Initial 7.6 7.2 7.3 7.1 6.6 8.2
8.7 8.9 7.8 8.7 Post- 8.0 7.7 7.8 7.6 7.0 8.7 9.2 9.5 8.4 9.2
storage Distinctness of image 13.3 13.5 13.2 13.5 13.3 14.6 15.7
16.3 13.9 13.2 Flip-flop effect A A A A A A A A A A Metallic
mottling A A A A A A A A A A Water resistance A A A A A A B B A A
Chipping resistance A A A A A B A A B B
TABLE-US-00025 TABLE 25 Example 2-31 2-32 2-33 2-34 2-35 2-36 2-37
2-38 2-39 Aqueous intermediate X2-31 X2-32 X2-33 X2-34 X2-35 X2-36
X2-37 X2-38 X2-8 coating composition (X2) Aqueous base coating Y-1
Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-1 Y-2 composition (Y) Clear coating Z-1
Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Z-1 Composition (Z) Evaluation result
Smoothness Initial 9.5 8.0 7.9 7.7 7.9 7.7 8.5 9.8 9.6 Post- 9.9
8.5 8.4 8.2 8.4 8.1 8.9 10.3 10.1 storage Distinctness of image
13.6 14.0 14.6 13.8 14.0 14.5 14.0 13.2 14.5 Flip-flop effect A A A
A A B A B B Metallic mottling A A A A A B A B B Water resistance A
B A B A A B A A Chipping resistance A B A A A B A A A
TABLE-US-00026 TABLE 26 Comparative Example 2-1 2-2 2-3 2-4 2-5
Aqueous intermediate X2-39 X2-40 X2-41 X2-42 X2-43 coating
composition (X2) Aqueous base coating Y-1 Y-1 Y-1 Y-1 Y-1
composition (Y) Clear coating Z-1 Z-1 Z-1 Z-1 Z-1 Composition (Z)
Evaluation result Smoothness Initial 11.5 13.5 13.8 12.2 12.5 Post-
12.5 13.7 14.2 12.8 13.0 storage Distinctness of image 18.1 17.5
18.8 19.4 19.1 Flip-flop effect C C C C C Metallic mottling D D C C
C Water resistance A A A A A Chipping resistance A A A A A
* * * * *